Many users use git from homebrew; once you do 'brew install git', the stub won't bother you, despite homebrew not overwriting anything. It is just earlier in the $PATH. And that's the issue with Windows: the standard installer does create python3.exe, it is just later in the %PATH%, because Microsoft placed the stub in one of the early directories. Normal, well behaved installer, which places its entry at the end won't be able to override anything.
