>>108900261A lot of people use Twitter as their portfolio site as well, so it's very common to have a post saying you're looking for work pinned on your dashboard and then just scrolling down allows you to see their work.
And there's a fucking ton of productions going on at once. A lot of pilots being made, a lot of commercials that need to be done, a lot of last-minute artists that producers need to find because someone on the team dropped out, and a decent sized number of pilots that get approved for a season and suddenly need an entire team for a year's worth of production.
Most studios have their own private recruiter recommendations network (As in, a website that gets shared with employee e-mails where you just submit names into basically a google sheet) where employees can submit names, portfolios, and preferred job titles of artists for recruiters to check out. I've gotten offered a board test before for a show that was not looking for people, but wanted to have my work on file and all because the instant you click on my Twitter page, you're bombarded with art.
Lots of eyeballs on Twitter, so it's a fast way to get exposure.