I could say the same about HN...

I couldn't. There's plenty of actually interesting and useful articles cited here, and then discussed (esp. if you're a programmer, but there's lots of non-programming topics discussed as well).

I can't say the same for Facebook. At best, you'll see cat photos and videos, which are OK, but not exactly intellectual, and I can get that stuff on Reddit's /r/aww anyway. More likely, you'll see a bunch of insane alt-right-wing "news" and memes and conspiracy theories passed around by your dumb relatives.

There's a lot of potential for timewasting on procrastination on both HN and Facebook.