If the fundamental nature of short-duration comment consumption is antithetical to fact checking, that's certainly a problem.
But it's still superior to uncited points, as it is ultimately verifiable.
In a choice between the two, I'll take the ill (claims appearing more supported than they are) for the good (inculcating a culture of transparent citation).
For example have you ever been in an argument where you recall reading a paper or statistic, but don't have it on hand? What if that statistic was a false correlation drummed up by a highly politicized thinktank?
This is why it's so important to not leave potentially misleading or outright wrong citations unchallenged. This is sort of how the 'vaccines cause autism' claims can quickly spiral out of control. It requires people to behave earnestly and not mislead with their citations.
By who? Do you seriously read an HN comment that states something you didn't already know with a citation you don't bother to click and then just go forward assuming it's scientific fact?
I don't even take publications themselves as scientific facts until they have been reliably reproduced or provide ample evidence.
I can make a claim without a citation, or attribute it to "some article I read awhile ago". No one can verify my original claim. Someone may attempt to dig up another citation refuting it, or find a suspect source making my claim, but these are inefficient ways of fact checking. And if I wanted to be a dick, I could claim that wasn't what I was talking about / my original source.
I can also cite my claim. In this case, 99% may accept it at face value, but 1% may fact check my citation and loudly pronounce it doesn't conclude what I said it did. The 99% then gain the benefit of an erroneous report.