Not quite, a forum for a specific niche wouldn't have their posts pushed to random users that do not care about that specific topic because those users wouldn't be on that community in the first place.

The Reddit Front Page and especially the Reddit mobile app with their push notifications, keep pushing posts from random communities to the front page AND to push notifications, which makes random people that do not know anything about the community to post random stupid things. I also blame the fact that the Reddit mobile app incentivizes people to comment with gamified streaks, so people are more incentivized to comment useless things on threads.