You didn’t read any of the article at all. This is a way of exchanging API tokens in an effort to reduce leaks.

What happens if eventually this is the only way of exchanging API tokens?

It won’t be, because “exchanging” API tokens isn’t something you’d normally do. It’s only done in the context of trusted publishing; in any other context you would continue to use the ordinary API tokens that this feature is built on top of.

You haven't read the article. :/

This has nothing whatsoever to do with installing.