Twitter at least was popular with somewhat actual leftists when it was new, specifically with occupy, people could communicate about protests with burner phones and you could recieve feeds in text message form so it was good for mass communication before it got locked down.
facebook was thought as leftwing in the 2009~2012 (round occupy), together with twitter
Twitter at least was popular with somewhat actual leftists when it was new, specifically with occupy, people could communicate about protests with burner phones and you could recieve feeds in text message form so it was good for mass communication before it got locked down.
I think the exodus from Tumblr also helped. Most of them went to Twitter.