The worst aspect is that she has been presented as a fully-fledged perfect heroine with no obvious explanation of where these skills come from.
Luke Skywalker jumped from crop-dusting farm-boy to ace fighter-pilot in a couple of days, with no explanation of where those skills came from, and nobody bitched about that, so I'm calling double-standards there.
But he didn't did he? He was a decent pilot and was able to get his X-Wing into battle without crashing it but he nearly got killed at least four times in the Battle of Yavin and needed others to pull his fat out of the fire. It wasn't until Obi-Wan
actually told him to use the Force, reminding him of his minute level of training, that he realised that he had an alternative to the clearly-inadequate targetting computer on the X-Wing. By
Empire Strikes Back, experience had made him a far better pilot and soldier but he was still very poor with his Jedi skills until Yoda gave him as much compressed training as he could (we don't know how long it took the
Falcon to make its journey from Hoth to Bespin but it could have been weeks) that he was even able to
hold off Vader for a short time. If Vader (a) didn't really think he was a threat and (b) had his own agenda, Luke would have been dead within a minute after that fight started. It would have been even longer for Luke to teach himself what little he could, mostly through Obi-Wan's journals on Tattooine before he was ready to rescue Han and, ultimately, face the Sith Order head-on in
Return of the Jedi.
Compared to Luke's long struggle to acquire skills, Rey's
really ace piloting skills and completely inexplicable expert-level lightsaber fighting skills is was ultra-easy for her.
And when, for example, MRA group Return of Kings organised a (feeble and ineffective) boycott of The Force Awakens as "SJW propaganda", I don't believe for one moment that they were making any sort of artistic judgement of the movie's writing, so I'm calling that BS too.
There will always be asses with an axe to grind. You can't judge a group by what, by your own admission, was a tiny minority.
The Force Awakens was largely met with a positive response by the fandom and so was Rey (although there was a lot of disquiet about the amount of hand-waving in the script about how she was doing what she was doing). It was hoped that
The Last Jedi would explain things but it did not and that is when the hammer really came down on her being a badly-written Mary Sue character that the writers were trying to reinforce by making all the other characters into imbeciles.
