This persisted for longer than it should have on Windows! I remember on Windows XP Home Edition, you could just press Ctrl Alt Delete to drop to the classic winlogon.exe screen and then log in as "Administrator" with no password!
By that time, though, Microsoft had implemented product activation. To my knowledge, no one ever cracked the telephone activation algorithm. That is, there were no tools to get a confirmation ID from an install ID. At the very least, no tools were ever made widely available, and don't seem to be even to this day. I suppose there wasn't a lot of need, since pirates just distributed volume licenced versions that did not require product activation (FCKGW).