It's a fair criticism, although again, this is a highly subjective situation. I mean, it depends on what you appreciate in storytelling. For me, I appreciate when storytellers tap into what seems to be universal to human storytelling. Characters who are just good at everything are universal. I mean, Achilles was surely a Gary Stu. That doesn't mean he was a poorly written character, even if by modern standards, having his one flaw be a literal gap in his god-given armor is somewhat eye-rolling. There's a power to stories like that.
In fact, setting up a character as invincible, only to reveal flaws as time goes on is a pretty standard thing. In an intended trilogy, I'm not so sure it's important for movie #1 to work as a standalone. Certainly #2 and #3 will not.
Trope has such a negative connotation, but... most tropes simply go back to universal storytelling elements. They're not really the negative they seem to be. You also clearly have no idea what psychotic means.
Again, it's entirely subjective. You can't keep coming back with "but it's obvious!" when it's entirely based on your own perception in the first place. It's obvious to you because she means that to you. She might mean something else to others. Actually, that Fanlore wiki article addresses Rey specifically now.
So, some say she's a Mary Sue. Some say she's not. Others say she's a Mary Sue but look at that as being a good thing. Viewpoints abound.