There certainly was a way for apps to do this. I had removed all third-party apps a few months ago (after allowing only a couple), but logged in a few weeks ago

There certainly was a way for apps to do this. I had removed all third-party apps a few months ago (after allowing only a couple), but logged in a few weeks ago to find two third-party apps that I hadn't authorized. It may have been a bug, and it may be different now, but there was certainly a period of time that apps could add themselves without my explicit permission.