I think missing from these conversations is the work environments involved. At a large company, a lot of what you said is true. At a startup, almost everything is in scope for everyone. I mean, someone has to do the thing. Part of the ask-telling is broadly communicating "I'm doing this unless someone else has already started on it or strongly wishes to do it themselves."

> And if you have a manager who often misses e-mails or takes forever to respond, then it comes across as trying to take advantage of that to do stuff they wouldn't approve, in a sneaky way.

I strongly disagree with that. Such a person is not a good manager. Their job is to be on top of things and keep their reports unblocked. If their reports are stuck waiting on them, or they claim ignorance of things they've been told about but neglected, they're not doing their job and have to be routed around.