Historical nitpick: it's less that Tumblr infected LiveJournal so much as LJ users were forced to move to Tumblr as LJ got increasingly difficult to use starting around 2009-2010. The migration had more or less completed by 2012. Tumblr being so much more of a "modern" social media platform where it was easy to repost content and you got a random jumble of posts instead of a carefully-curated set of friends made it much easier for social justice thinking to spread.
I think the whole shift to showing users a melange of content instead of a staid list of people the user chose to follow was a big driver of that sort of thinking. It allowed ideas to spread, upped controversy, and drives that sort of "we must purge this!" was of thinking.
Historical nitpick: it's less that Tumblr infected LiveJournal so much as LJ users were forced to move to Tumblr as LJ got increasingly difficult to use starting around 2009-2010. The migration had more or less completed by 2012. Tumblr being so much more of a "modern" social media platform where it was easy to repost content and you got a random jumble of posts instead of a carefully-curated set of friends made it much easier for social justice thinking to spread.
I think the whole shift to showing users a melange of content instead of a staid list of people the user chose to follow was a big driver of that sort of thinking. It allowed ideas to spread, upped controversy, and drives that sort of "we must purge this!" was of thinking.