It's a preemptive defense against methodology cynicism seen often on sites including but not limited to Hacker News. I've been guilty of including such defenses myself over the years because I've gotten annoyed with receiving such cynicism.

Look at the top comment on their previous HN submission: https://news.ycombinator.com/item?id=48839886

Ugh, that is bad, and I'm sorry I didn't see it at the top of the thread yesterday.

Really, the deeper problem is the upvotes that cause such posts to rise to the top of a thread and stick there, drowning out curious conversation and giving people a bad impression of the entire community. Unfortunately, the upvote problem seems basically unsolvable - people don't do it consciously and it's very much a tragedy-of-the-commons problem. So we're stuck with moderation on the comments.