> it's the ensuring that the library got everywhere it needed to go and that the new release of the other users of that library didn't introduce any bugs.

And guess what, you have to do the same thing with microservices. You must ensure that all its clients are pointing to the correct version, and you must ensure that the new version didn't add any bugs in the clients.

Adaptations for new service versions will also get into the release queue, and can also get blocked by other stuff.