While I think the primary reason has already been covered, if we think it from their perspective of "equality, equity and inclusion", we know equality doesn't matter and inclusion isn't really a problem given the fairly open platform.

This leaves equity, and on average men perform better on Twitch than women long-term. Women attract initial viewers easier, but said audience is quicker to leave compared to those of male streamers, probably because the men have to work harder to actually entertain their audience.

What does this mean? Encouraged simping aka more business, probably. But worth contextualizing in the language of progressive tech, which is that women are oppressed and need help.