But it is the job of browser developers to build programs that serve their users. If I, as a user, want to autocomplete a form field, the website operator doesn't get a say in whether I can do that.

The settings that come with the markup are best understood as a recommendation, a slight hint that autocomplete might not be appropriate here. The final say is always with the user, though.

Sadly, through over-usage on the part of website operators, this hint has become utterly useless.

But completely ignoring it isn't super helpful either. I run into more issues with chrome autofilling in forms inappropriately than I ever did with forms that I couldn't autofill.

I think the solution is to follow the hint, but give users an override button next to or inside form fields that have it set to off.