It’s there to get it away from the other categories. Every category isn’t just a game, there’s other stuff like events, just chatting etc to cover any content that isn’t specific to a single game (like a gaming related podcast for example), so playing a game isn’t required you can just talk at the audience. People who make the sexual content were using those more generic non-gaming categories (as well as popular gaming categories but having the game running in a tiny box in the corner) but advertisers took issue with advertising on the sexual streams, so Twitch made ways to segregate them from the content advertisers wanted to pay for.
This is also a proposed wealth tax not just an income tax, the US would probably do something like tax US citizen ultimate beneficial ownership of assets held which can be traded on US exchanges, so unless someone entirely divests there isn’t a legal tax avoidance strategy apart from the exit tax.
Honestly 2% on billionaires is too low imo. I’m in favor of starting lower and having a progressively increasing marginal wealth tax, like 1% on all assets over $10M, additional 1% on all assets over $100M, etc.