[erebus_rex]

Can't speak for OP but Tumblr has a pretty big SJW subculture; screenshots from more esoteric or radical discussions get some ridicule on reddit and elsewhere. Check (the equally toxic) subreddit tumblrinaction for a sample of this type of content. I can't tell you how representative that is of the whole site though as I am also not a tumblr user.

[free_everybody]

I'd like to point out that you're referencing hand picked, extreme examples of a community. There's a massive bias. You have no way of knowing what Tumblr is like based on these examples.

[zaarn]

From my experience, TIA is rather representative once you remove the various art blogs and their reblogs.

As I've stated in another comment, several creators I enjoy have been massively bullied by wider communities on Tumblr until they left.