If what you say is true, I assume the main drivers would be an increase in users (possibly fleeing from Reddit which has well and truly turned into a cesspit) and the general polarisation of politics in the developed world.

It is worth bearing in mind that everything always seems like it was "better in my day". I'm not here that long myself (maybe I'm the problem!) but going back four or five years, HN was kind of known in some online circles for its poor takes on certain subjects.