Are primary or secondary school grades important?

One of the more curious and strange cultural phenomena that has existed for many decades and to this day, is this notion that primary and secondary school grades are utterly important. You see this all the time in all kinds of TV series, cartoons and so on (although admittedly significantly less today than 20 years ago), ie. parents being upset when their children get poor grades in school (The Simpsons might be one of the few cartoons that still play on this trope to some extent).

And this isn't restricted to fiction, as it happens a lot in real life as well. This... cultural custom that primary and secondary school grades are of utter importance, and emphasizing to children how important it is, and sometimes even rebuking them if they get poor grades.

In the United States in particular this is a very detrimental culture because the pharmacological industry is abusing and taking advantage of this by convincing parents that their children absolutely must take concentration-enhancing drugs ("ADHD medication" they call it, which is just complete bullshit) or else bad things will happen. An absolutely staggering amount of children in the United States are being drugged in this manner by well-meaning but misled parents.

But the thing is: Why? Why are those grades supposedly so utterly important?

I'm asking 100% seriously.

I have never, ever, not even once, been asked for my primary nor even secondary school grades anywhere. Not in any job application or interview, nor anywhere else. Literally nobody cares about those grades. Not employers, nobody else either. In theory someone might perhaps be interested in your high school grades if that's your highest form of education, maybe, but literally nobody cares one iota about your primary and secondary school grades. Nobody gives a flying fuck about whether you got an A or a C in second grade. It's 100% inconsequential. Literally nobody is interested.

So why, exactly, are those grades considered so important when children are going to those classes? What for?

The main drawback of this is, as mentioned, particularly in the United States where the "ADHD" drug industry is literally a multi-billion-dollar industry which is by far and large a complete scam. And what's scary is that it's completely legal scam.