I feel a little more ambivalent than usual in this particular case. It's probably because I have little good to say about the AV vendors' side in the matter either.

It's a little different from something like the IE era browser wars, where MSFT was (more than nowadays) able to push de facto web standards, which would then affect users on all platforms. Or the chokehold they and Alphabet have on email, which directly drives people and organizations to commercial email services (namely theirs). Or the fact that approximately 100% of PC games are on their OS and oh oops now they own most of the biggest video game studios too, curious!

By comparison, antimalware is more tightly tied to the OS in the sense that commercial antimalware products for other platforms than Windows are fairly niche and exploits tend to vary a lot by platform. Since Defender is a part of Windows, it doesn't really hurt MSFT's bottom line if someone decides to install a third party antivirus, except when issues like this very outage give a bad name to the whole OS and company. Not that Microsoft's own code is somehow foolproof, but you could argue it's better to have a Defender bug every now and then than CrowdStrike bug today, F-Secure bug tomorrow, Trend Micro next week, Kaspersky soon after than, then Comodo and Check Point followed by Trend Micro again…

So if we are to accept that the plan to give Defender special treatment in the Windows kernel is not for the purpose of selling more copies of Defender (since it comes built-in with Windows anyway) and that it would reduce the occurrence of outages like this one, the main downside (if you consider it such) is that it would instantly obliterate the commercial malware blocker industry. So I guess that's pretty anticompetitive.

And tangentially, having to beg the EU to make big brother Nadella share kewnel intewface with poor widdle AV shops kinda shows the industry is already EEE'd to a terminal stage.

Now, I think all of that is being overly generous to the titan of monopolism that is Microsoft Corporation, but I can indulge in a little bit of lawnmower anthropomorphization when it's mowing a lawn I don't like anyway. Was it a good or bad thing that the 2009 agreement with European Commission required this provision for security vendors? I don't know. Microsoft sure likes to say "regulation bad" though.