I won't switch her browser to firefox. I'm not her tech support although I am in tech. Welcome to 90% of users.
If I was her tech support, and I wanted to prevent the browser being changed by the user, I would.. Explain it to the user. And if they still changed it after that - guess what, that's their choice. But I could, just like you, prevent that with group policy. And when you do that, you won't get prompted to change it, just like my work laptop doesn't prompt me to change it. So what is the issue? The fact that if you do your customization and don't complete the full power user process, the OS can't tell if it was a random web page that did it? Maybe MS should collect some more telemetry on your laptop and run a compute-heavy AI to figure it out?
>I have spent so much time disabling all these ads on my Windows 10 Pro machine.
and why in the world would you do that? it literally takes two clicks in many different pieces of software that are available.
for the 90% of users - guess what, they wouldn't know about 1drive if windows didn't display an ad for it. What you call an ad, my wife calls helpful suggestions. When you're grocery shopping and you see a banner "apples 10% off today" that is also an "ad."
Microsoft is not a bad actor. The "google is worse" talking point is one I never stated, and a strawman you made up.
What you call "Ads" are simply defaults. And you can disable them in about a minute with one click in an app. You don't like edge at all? Guess what - there are fifty things you can do to completely disable or remove it - like change security on its folder or run a single powershell command to uninstall it.
Windows is an OS that is tailored to its users. That's not you - don't use it if you don't want. Here in the real world though, any power user simply changes the defaults in a couple of minutes, and at work there's a corporate image with all those turned off already.