It’s curious because Microsoft owns the operating system and was more than capable of designing in such a way that would allow sysadmins more control over third party browsers and software. Firefox would have been willing to work with them to provide the necessary levers. They already do with group policy.

“Security” is a term that shuts down arguments and silences all accusation of anticompetitive behavior. And they absolutely abuse that. You don’t think the bean counters are ecstatic about the fact that they have effectively been able to turn every IT department in the country into Edge salesmen? You don’t think there was a board meeting where the benefits of that were discussed?

Back when Internet Explorer was still a thing you could configure it with group policies domain wide. If Microsoft implemented similar features for Edge in an active directory environment I can definitely see the appeal. Not to say similar isn’t possible with Chrome or Firefox, but first party integrations in a corporate environment tends to be the path of least resistance.