One can keep doing MVC just as always, no need to jump into Razor Pages with code behind, or the minimal APIs designed to cater to JS devs.
Just like JakartaEE isn't fully 100% Java EE, yet most stuff works the same way.
Web Forms is deprecated since around 2010, while 12 years old MVC is a matter of creating a new .NET Core project, even WCF is now mostly supported on CoreWCF as Microsoft has forced to support it.
Windows developers don't like Python 2 vs Python 3 experiences, and have voted multiple times when Microsoft tries to play Apple.
This is hardly like FE frameworks having been doing since jQuery.
Comment last week during a PR, why are we still using webpack instead of XYZ.
You can run JS from 15+ years ago in the same vein.
Thankfully only have to deal with JavaScript on the browser.
I have had to touch. Net code that hasn't been updated in years and bring it current. It isn't fun.
By the same token, I lost about a week and a half recently updating a front end project that was started about 5 years ago.
I'm either case, .Net is definitely not the panacea you seem to assert that it is.
It is still MSBuild, Maven and Gradle after all these years, three major IDEs, most libraries just work, there are hardly talks about why we are doing it all wrong and use framework XYZ or build system ABC instead and so on.
No need to jump into framework of the month for backend.