I think this is a misunderstanding. Microsoft didn’t ask IBM something for logging users in in the DOS days. They wanted a way to reset via the keyboard. IBM provided that with Crtl-Alt-Del.
Windows didn’t use this for anything until NT in the early 90s, and it was their choice to do so. Nothing to do with IBM.
When people ask Gates about Ctrl-Alt-Del they’re obviously asking about why it was chosen for a login sequence, but I believe Gates conveniently answers a different question to make it seem like IBM had something to do with that choice.
