In the case of Reddit, it was purposefully trashed by its new owners who decided that anything less than a east-coast-lib groupthink would prevent growth, or something - or maybe they are just incompetent. Feels a similar story with Stack-Overflow.
a) Reddit is a gigantic mixed bag of quality, and thinking Reddit is “all bad” is admitting to not understanding how to use it, and
b) being unable to understand that the category isn’t actually “forums” is sad. You can get this level of quality (which is to say, not the real draw of HN in the first place) by directly visiting the sites posted here.
b) Hacker News and subreddits are variants of forum though? I understand your idea of being able to get this yourself on the linked pages, but I have to say I really enjoy the preselection hacker news users do for me.
In short, Reddit serves a purpose that Google used to serve.
That's true actually. I usually use google + reddit to find "real people (TM)" testimonials for medical treatments that can't be found otherwise.
b) The link aggregation and the conversations are two distinct features, and only some tiny percentage of good content actually makes its way here, and even when it does, HN is extremely temporal, so if you "miss" it, you're SOL.
But I really, truly, emphatically, want to make something clear: HN users are not in any way immune to any of the things you seem to take issue with over on Reddit. Your problem isn't with HN or Reddit, your problem is with people, as what you've listed is true and inherent in any collection of humans interacting with one another (specific ideology notwithstanding).