> I'm surprised to hear people keep re-learning this lesson. Back when web forums were popular, this was basically the one big mistake I kept seeing people make. Way too much compartmentalization.

Ahh yes, the “General” section of phpBB. To be fair though a whole generation as come online since then, that never had an opportunity to learn for themselves yet. The internet itself moving away from small niche sites/forums to subreddits/groups/categories under big monoliths.