Something is stopping them, otherwise they'd do it. Even if that's purely psychological, that's no less real to them, and the outcomes are clear.

A close analogy might be weight loss: "nothing" is stopping anyone from eating less, yet most Americans eat more than they should.

Right.

Going to the office meant a baseline of 7,000 steps a day, plus quite a few flights of stairs. Plus it was easy to go to salsa and gym after work (because I was already out of the house, so it was easier to to talk myself into going).

I struggle to do any of those things when i'm remote. I know perfectly well that I physically can, but that psychological inertia is extremely powerful.

Personal discipline, or the lack of, is a thing.

Plenty of people benefit from imposed structure in their lives.

Yes, it's bad, yes, it's sad, but that's life. It's not all idealism and dreams.