I'm not sure where you're going with that. Everything has bugs.

You point about API changes is valid, but that an API is "complete" doesn't mean it's "done". It takes a LOT of testing and tweaking to get an API "just right"

No API is ever done. They always evolve over time. If you do something drastic that breaks backwards compatibility in a big way, you can release 2.0.

The 1.0 version number is arbitrary and for marketing purposes only.

Right, which is why everyone should feel free to use it.

Programmers should know better than to trust a version number.

And yet they don't. They get scared by low version numbers. And so do their managers. That's why it matters.