I'm super into the hearthstone scene, so maybe I can add a few things.

You mention getting more twitch views. This is really the main reason people thought something fishy was going on with MagicAmy. There are no twitch views. She never streamed. She managed to build up such a cult of personality through chat and reddit that her twitch account had over 10,000 followers and a nonzero number of subscribers, all the while having not once streamed a single game of hearthstone. That's perfectly fine, there's no rule against it or anything, but it's probably the main thing that piqued suspicions.

Is it sexist?

Maybe. There have certainly been hearthstone-based witch hunts before which didn't involve women and were similarly myopic. I think the guy who wrote the reddit post that initiated the whole thing might actually be sexist. After his 15 minutes of fame for successfully starting the magicamy witch hunt, he made another rambling post about win-trading. He said he wasn't going to name any names, but one of the people who was in top 16 win-traded and got coached to high ranks. Except that he used female pronouns to refer to this unnamed person, which leaves almost zero ambiguity as to who it is since there is only one woman known to have made top 16. And this person is a popular streamer, so it's pretty much provable that she made it to top 16 with no funny business since she streamed the whole process.

If a guy was using a girl as on screen eye-candy to get more twitch views and ad revenue, that's smart business, as long as she was paid equally.

If you're upfront about it, sure. But if you claim to actually be a Korean girl when you are not, that's not cool.

I'm really not sure what to think of this whole situation. There's some strong circumstantial evidence that Magicamy is not exactly who she says she is (which I won't link here, because it's probably doxx). But if we got this wrong, it really would be awful.