Only Typescript is in-house. Others are acquisitions. Do you remember Embrace, extend, and extinguish times?
https://en.wikipedia.org/wiki/Embrace,_extend,_and_extinguis...
https://en.wikipedia.org/wiki/Embrace,_extend,_and_extinguis...
If you write a project in C#, you've committed to it and it's ecosystem. Getting out of there when MS makes a choice you don't agree with is going to be near impossible.
In fact when Microsoft purchased GitHub, quite a few people did leave and close their account. But GitHub already had such a monumental market lead that the departures ended up being a drop in the ocean.
To be honest, I’m still waiting for the moment when Microsoft managed to fuck it all up like they did with Skype.