Nothing like FB/Insta (which I am not using), but for me HN still counts.
That common problem is the voting system—likes/dislikes, up/downvoting. There are multiple problems here and there's much to say about it, but perhaps the worst is that it's polarizing. Frankly, I'd like to see it either eliminated or the rules substantially modified. For instance, downvoters are anonymous and they affect the outcome without ever having to say why they disagree†. That's not a good system, if one disagrees one ought to have the guts to argue why.
Of course, those who run the show would disagree as fewer people would participate.
† On HN, if, say, a poster receives 10 upvotes and 10 downvotes neither the poster nor others are aware of the fact. Effectively, a controversial topic where opinion is split down the middle turns out to look like it's a matter of little interest to anyone. That doesn't make much sense.
HN is horribly broken.
Although Reddit is a very low bar.
If you like your opinions strong and you think for yourself and you resent being signaled which way to respond and think, you'll be down voted and treated with condescending comments by those who like echo chambers of agreement.
It's not the downvoting that's the problem it's that they often do so anonymously without comment. For example, as I've mentioned my post above stands at zero votes after oscillating as high as +3 (although it might have been higher without me knowing about it).
I believe in debate and if they disagree that's completely fine but I want them to explain why as by doing so things move forward. HN's system doesn't encourage that.
In this instance I neither know why they downvoted nor how many votes there were in total. In politics this matters. If say I get 3 votes for and 3 against it's reasonable to assume I've made a reasonably balanced commentent on a rather unimportant matter. If I get zero votes after 3k have voted for and 3k against then the matter is important to many but neither I—the poster— nor readers are adware of the fact.
When votes oscillate around zero I take it that my comment is pretty neutral, essentially a statement of fact. Shooting the messenger is a well-known phenomenon.
Incidentally, something I've noted is that I'll often get downvoted days after the main activity stops. Vote stats therefore should be timestamped. It occurred to me HN could do an analysis of voters together with their actual posts. Anonymous stats like that could tell us much about why Social Media is in such a mess.