>>45912080Boils down to a lot of people use Twitter. Like
>>45912129 said Tumblr banning NSFW, although they're doing a shit job at it, and becoming more shit of a site in general causing a migration to different sites, like Twitter.
Pixiv was doing some weird copyright thing where they tried to claim all art on that sight as their own, at least that's my understanding I may be wrong on that. Whatever it was also caused an exodus of people to move to different sites. Mainly Twitter as well.
tl;dr Twitter has a large following which means more eyes will be looking at your art so moving their is a no-brainer.