> It's not its lack of features that people are leaving, it's that the rest of the Internet 'gained' features, specifically Facebook, Reddit, and Discord,

Sorry, no. I don't think you get it. People weren't leaving because reddit had threaded comments (or something dumb like that), and that was so great they just had to spend more time there. "Features" have nothing to do with the issues.

> and they consume more of every potential user's attention.

Metafilter's always been so small (and must remain so to work), that concerns like that are totally off base.