When Steve Jobs introduced Face Time he said that they were working on a Windows/Android version as well. If they had actually released one I think Skype and Team Meetings and Zoom would all have a smaller market share just because Face Time would have had an instant market and a reason for Android and Windows users to select them instead. I don't know why Apple didn't release those versions. They were probably other software companies back then but none with the instant market that Apple had even 10 years ago. Now my family uses Zoom because of the number of Android and Windows users that can't use Face Time.
Guessing Apple looked at how things were (got sued by VirnetX, started and run at the time by former NSA employees) for a software patent that prevented Facetime from being direct phone to phone and VirnetX would not take money to allow Apple to use this type of connection for Facetime, Apple had to switch to a phone to server to phone model) and the constant harrassing from the govt directly about encryption and figured if they'd roll out the Android version (so they'd be the no 1 encrypted chat / video service), it would not be worth it. JMHO.