At least .NET is very capable of allowing you to support third party libraries. Heck, even ASP .NET Core isn't built-in anymore, you get it through NuGet. So you're not stuck with the standard libraries.
ASP isnt included OOTB anymore, so if you want to do web dev in .NET you have to install it, they decoupled a ton of things from the core of the language.
But when you're replacing, like, much of the standard library, you have to be a bit sad about all the interop work that falls on the user. It should instead fall on the makers of the bad standard library.
Microsoft is more likely to just create new alternative libraries / classes to the standard library. They drop new things all the time that improve on old approaches. Look at every way you can make a GUI in .NET from Microsoft as an example of this.
People have no issue using third party libraries in other languages to get more done than the OOTB libraries.
