I'm not here talking about people who publish videos about things like politics or religion and who disable comments. While that's annoying too, it's a somewhat different issue I won't go into in this post.
I'm talking about popular youtubers who consistently disable comments on all of their videos as some kind of "protest" against the YouTube comment system, or even more egregiously, because they don't like their average viewer (which is quite a douchebag attitude to have, but more on that later.) And as said, this is not about people making videos about controversial subjects like politics, but eg. people who make video game reviews, "unpacking" videos, puzzle solving videos, "let's play" videos, and the like. In other words, not people who don't want to hear what the "enemy" has to say, but have other equally dumb (or even dumber) reasons.
The craze of disabling YouTube comments started most prominently when YouTube radically revamped the commenting system a couple of years ago. Lots of people jumped on that bandwagon when it happened, and while the fad has almost completely died out, a few stubborn individuals keep doing it to this day. (There are also other youtubers who do it for other reasons than exactly that, but they are nevertheless very similar.)
In order to understand why I consider this rather obnoxious, I need to explain how the new system has affected the quality of comments.
There were two major problems with the old comment system that were addressed by the redesign (one of them completely, the other partially): There was a size limit to comments (I think it was 500 characters), and comments were completely unthreaded.
The latter thing made it very difficult to follow any kind of conversation between commenters. Sure, you could "reply" to another comment, and a "in reply to" link would appear on your comment, but these were just links to individual comments, which were all spread among all other unrelated comments. There was no structure to it, and it was basically impossible to read all comments that were related to the same original comment. The new system puts all replies under the original comment, which is significantly better. (It's not perfect because not all replies are for the original comment, but someone else in the same "thread", but at least it's miles better than the old system.)
The character limit was, however, even more annoying. 500 characters are enough for a quick comment without much content, but it was extremely limiting when trying to express your views on something in even slight detail. You run out of your allotted 500 character really quickly. Removing the character limit was one of the best changes ever made to YouTube.
Some could argue something like "if you can't say what you want to say in 500 characters or less, then it's too long", but that's simply not true. Being able to actually say what you want to say increases the average quality of comments significantly. I have clearly noticed this since the new system has been in place.
Sure, there are still dumbasses and trolls (there will always be), but on average I really have noticed the average quality of comments grow significantly. People are now able to have actual intelligent discussions with each other, and to express their views and knowledge in full. Many of the comment threads on some videos I have read and participated in have been of the highest quality in terms of content that you can ever expect on a public forum. The old system hindered this significantly (both by the character limit and the lack of threading.)
Being able to post links has also been a big plus. Of course people immediately protested that comment sections will become full of spam links and links to harmful websites, but Google seems to do an excellent job at filtering those out since, believe it or not, for the entire duration that the new system has been in place, I haven't seen even a single spam or unwanted link.
In fact, the amount of spam in YouTube comments has dropped almost to zero with the new system. With the old system spam was a real problem, especially in very popular videos (those with millions of views.) Often you could browse the comment section of such a video, and each third comment would be the exact same spam message. With the new system I don't remember seeing but perhaps one or two spam messages (and even from those few, none contained any links). That's during the last year or two that the system has been in place. (I have no idea how Google does it, but it seems that they have some pretty good filtering going on.)
The biggest criticism of the new system was, of course, that you are forced to have a Google+ account in order to be able to comment (even if you are commenting on your own video.) The criticism is that all of the above could very well have been implemented without forcing people to make such an account.
There is a good point in that criticism. However, and this is my point, disabling comments as a form of "protest" against this system is idiotic, completely useless, and in the end very disrespectful towards your viewers who have done nothing wrong.
It's not your viewers who put up the system, so why are you punishing them? It makes no sense.
Some popular youtubers who jumped onto the bandwagon made lengthy videos ranting about the new system and arguing why they are disabling comments from now on. Many of them just grew out of it during the years and have re-enabled comments and forgotten about the whole thing. A few stubborn ones, however, are still doing it. Many of them just keep them disabled out of strange principles, not even bothering to say why anymore.
For example, one very popular video game reviewer regularly disabled comments and always posted something like "comments have been disabled due to the new commenting system; see this video for why", and a link to a video where he rants for an hour about why the new system is the end of the world. After some time, however, he hasn't even bothered doing that, and simply keeps comments disabled with no excuse whatsoever. Most obnoxiously, though, recently he started allowing comments, but has them set as moderated (ie. he has to approve each one before they become visible), and just doesn't bother with them at all. In other words, you are free to write comments, but he will never read them and they will never become visible. And I'm not making this up, because he said that himself, quite directly and unambiguously. He also ignores any pleads to just open the comment sections.
He is not the only one who keeps comments disabled out of idiotic reasons, or not even any rational reason at all.
I find this behavior extremely obnoxious and disrespectful towards your viewers, especially when it's done so blatantly.
Sure, as said, there will always be dumb people and trolls, but who cares about them? The average quality of YouTube comments has increased very significantly after the new system has been in place. By disabling comments you are denying your viewers a channel to express themselves about the contents of the video, and to have discussions with other viewers. Openly and blatantly expressing that you are in no way interested in reading viewer comments is one thing in itself and a rather douchey thing to do, but stopping people from even having conversations among themselves is even worse. It shows that you have no respect whatsoever towards them.