[mark_integerdsv]

>why can't the SJW's and their ilk who came late to the party go find their own place?

Because their cause is evangelical in nature.

Were it just kept to Tumblr then they wouldn't have much with which to stoke the fires.

SJW's are specifically about pointing out to others where they are wrong/insensitive/racist/sexist/ableist/etc.. if they just kept to themselves then who would they persecute with their 'justice'?