The main problem I have with the trans community on Tumblr is that it's basically divided itself into factions which spend most of their time insulting each other. Sometimes I see more posts questioning the validity of other people's trans experience that I do people just talking about their own trans experience.
It particularly annoys me that people get called transtrenders, and that people say that teens are just being trans to be cool. Because we all know that being transgender is so easy, and society is so accepting, and this is totally something that people do by choice that gets them lots of friends.......
I think that it's highly likely that there are a bunch of young people on Tumblr who are just experimenting with their gender and maybe some of them will go on to transition permanently, and maybe some of them will realise that they are happy with their birth gender and that's fine too. I don't see why anyone should attack or belittle them for it.
There also seems to be a big bias against non-binary folk on Tumblr - If you don't consider yourself 100% male or 100% female then you aren't welcome.
Sometimes there is great content on there and I do follow a couple of trans guys who post interesting stuff but it is definitely not a safe space a lot of people.