The term "reverse racism" is rather popular among social justice warriors (and goes way back, at least 10 or 20 years, when "social justice"/"intersectional feminism" was more commonly known as "multiculturalism").
The thing is, I don't remember ever seeing or hearing that term used by skeptics, by the anti-SJWs. I don't even remember seeing it used by actual white supremacists and racists (although I haven't seen much material by them, since I'm not exactly interested.) I have ever only seen it used by social justice warriors.
Why do social justice warriors love to use that term? Why have they coined it in the first place?
I think they like to use that term to distinguish it from their own definition of "racism", to make it a completely separate and independent concept, and thus easier to attack and delegitimize.
In their narrative, only white people can be racists, and only non-white people can be victims of racism. To them, the notion that a non-white person is racist, or that a white person is the victim of racism, is simply impossible. To them, it's a completely absurd notion.
Thus they coined the term "reverse racism" to refer to allegations of prejudice or discrimination against white people by non-white people, because of race. It's not "real racism" because, as stated, that's an impossibility, so it needs another name: "Reverse racism."
Of course now that they have coined the term and the notion, they can proceed to delegitimize it, ridicule it, and attack it. "There is no such a thing as reverse racism." That's what they mean when they say that: In other words, that racism against white people is impossible.
Funnily, I agree that "there is no such a thing as reverse racism". However, with that I mean something completely different than what they mean. With that, they mean that racism against white people is impossible. What I mean with that is that the term itself is completely nonsensical.
So yes, there is no such a thing as "reverse racism" in the same way as there is no such a thing as "reverse murder", or "reverse theft", or "reverse arson", or "reverse jaywalking". It's just a completely nonsensical concept. It makes no logical nor semantic sense. What would "reverse murder" even mean? It's a completely illogical pairing of words. (I suppose one could argue that "reverse murder" is bringing someone back to life, but that's quite stretching it, and not a term that one would use for such a situation. It would be a completely silly expression to use in that situation. Would be more of a joke than anything else.)
In the same way as there is no "reverse murder", only "murder", likewise there is no "reverse racism", only "racism".