Yes, and I don't think it's just people using upvoting as bookmarks (most people I know don't do that).

I think it has to do with the fact that HN is a very diverse mix of folks (technical, non-technical, working at startup, working at big co, web devs, mobile devs, infra dev, etc). There isn't a concentration of ML-technical folks like you might find on /r/machinelearning (decent technical ML discussion). Instead you have here a mix of futurology speculation and tutorial discussion - lots of introductory material of highly varying quality (since the people upvoting don't really know if it's good), science fiction passed off as credible opinion, highly technical ML posts that get upvoted a lot but no comments, etc.