Is she really as big a name as you're treating her as? I've not seen her posted her ever until your post, none of hundreds of pianists I follow have played her music, have not seen her mentioned one time in r/piano etc.
I don't know what you call "big," she has 150k subscribers on YouTube. And her music is not top-tier, so I see why not many musicians play her music. Despite not being on par with the "greats," there's no way she should receive as much hate as she did on that reddit thread (and it gets even worse on TalkClassical).
It's called "Tall Poppy Syndrome". Often exhibited by jealous failures or blacklash directed at someone with success who is bragging far too much. Most likely you are dealing with jealous failures.
Perhaps the same "hate" for Jacob Collier?