The elephant in the room is that 4chan's average quality of content is by far the worst of any major forum platform. The "bump" model is also used iirc by most bbs or older-style internet forums. In the modern age, incel forums are probably the most popular of these older-style forums (and surprisingly they probably have only slightly better average quality than 4chan).
So, correct me if I am wrong, but the bump model usually results in shitty average quality of information.
As the bump model needs heavy moderation as the upvote/downvote system is a form of self-moderation/censorship. However, the entire appeal of most sites that use the bump model is to shitpost or be edgy...
Honestly, the bump model does sound intriguing from a utopian, critical-thinking first, free speech first-principles perspective, but I'd like to see an example of a successful popular forum that implements such in reality.