> Actual discussions between scientists are much more lively
This only works because the people are vetted. Almost everyone on HN is a rando and randos had better be able to back their assertions up. Otherwise you just end up spending all your time humouring crazy people.
But a scientific article is not an exercise in argumentation. The main purpose of citations is to guide readers who are new to the field, give credit to readers who are experienced in the field (indeed, many criticisms of an introduction or discussion from reviewers amount to "wtf you didn't cite that paper I wrote"), or contrast with previous results. It's not "here's why I'm right" but "here's how existing stuff relates to what I've found". The tone is much less assertive. Scientists are not a very assertive bunch in general.
This only works because the people are vetted. Almost everyone on HN is a rando and randos had better be able to back their assertions up. Otherwise you just end up spending all your time humouring crazy people.