I think it comes from their culture "growing up" in hostile parts of the internet (twitter, Reddit, HN, etc) and so having to hedge every statement with excruciating delineation of edge cases and precise scoping lest some sneering POS leave drive by comments that twist their words into some straw man that the local majority will be against.

Basically it's a defense mechanism against adversarial HN commenter type behavior that's been cargo culted a couple times over and doesn't actually service it's original purpose anymore and is just a group signaling mechanism.