Wow, you are so "The WELL" circa 1997. Communities grow (and thrive, even) as the swell of users come and, ultimately, go.
Besides, there are more than enough subreddits to subscribe to that are almost completely devoid of any "drivel" you refer to (r/science and r/TrueReddit being just two; and I contend that r/programming and r/coding are even more useful to hackers than HN).
Besides, there are more than enough subreddits to subscribe to that are almost completely devoid of any "drivel" you refer to (r/science and r/TrueReddit being just two; and I contend that r/programming and r/coding are even more useful to hackers than HN).