@mike It seems as if @Gargron missed the time when Micro$oft's Exchange (their "email") server broke IMAP support with pine (y'know, the REFERENCE IMAP client)?
Heck, even I missed that until Tim Newsham pointed it out to me, because even though I was working somewhere as a Network Security Specialist and was administering (at the time Exchange 2003) I wasn't testing it with other IMAP clients, because I wasn't getting paid to do that and was using elm/mutt/etc. on my UNIX shells elsewhere.
So, not too sure if email is really a strong counter example for the "embrace extend extinguish" paradigm? I mean, sure SMTP (and even UUCP) server and client implementations exist in abundance, but you don't have to look very far to see how some of the big surveillance capitalism bullies have made it very adversarial.
e.g.
https://www.jwz.org/blog/2023/12/gmail-sucks-water-is-wet/
https://www.jwz.org/blog/2014/05/google-has-most-of-my-email-because-it-has-all-of-yours/
https://www.jwz.org/blog/2015/03/google-seems-to-have-broken-email-forwarding/
https://www.jwz.org/blog/2023/09/today-in-email-hegemony/
https://www.jwz.org/blog/2022/09/the-oligopoly-has-won/
https://www.jwz.org/blog/2022/08/today-in-google-broke-email/
Last I checked, Micro$oft still *prefers* that Outlook uses MAPI (their own, proprietary BS with Exchange which other companies such as Zimbra have gone to significant lengths to reverse engineer with their ZCO [Zimbra Connector for Outlook]).