This is one reason HN is often not-subtly mocked. We condone the behavior by not shutting it down. And the negativity consumes a lot of the air in the room.
I think it's just that two things are true at once. All the mockery and criticism is accurate, but I think it's also the case that the signal to noise ratio here has remained unusually high for an unusually long period of time. (Probably due to years of tireless thoughtful moderation.)
This can still be like being the skinniest kid at fat camp. If social media in general is bad for your mental health, I don't know if it's a ringing endorsement to be the "least bad for your health."