> They're always overly-complex descriptions of the mechanical changes and have no sense of motivation.

This is funny to me. Coding isn't a main part of my job, but I know someone whose it is. And he says the exact same thing about his colleagues. And not just about PRs, but also comments in code in general.

Recently?

It was already a well-known review point way before LLM's. Every book about code cleanliness has some point about "write WHY not WHAT when commenting code". It's a point everyone makes, because it's such an ubiquitous thing.

Of course the standard bad example is

    // add 1 to a
    a++;
While an IMHO good example would be when normally you wouldn't expect this addition, so you'd comment

    // the flipDinkleWooptie method doesn't add one in this case
    // because there is no wooptie register, so we manually
    // add one here.
    a++;

He's been complaining about this pretty much since we started working, more than 10 years ago.