Probably because you seemed to have partisan worms in your brain. Twitter HAS been burdened by the "extreme right" abusing its platform. Its the entirety of the debate around what should be moderated on twitter. Insisting that this can't be true because "the left" hasn't had an exodus doesn't seem to make sense to me.
There is simply not many places to go. You can’t really keep running t from madness all the time since with social media platforms the destination must be at least somewhat inhabited, and also the exodus must be coordinated.
It’s more like moderate left left left, the extreme right were expelled, and extreme left stayed out of grit and also because Twitter was sort of left to them .