Why is this restriction allowed? Isn't this a violation of the browser choice consent decree, or has that expired?
Edit: I see this is "Windows S", which inherits from the failed "Windows RT" the attempt to jam everything into the walled garden of the store. This is unlikely to work and I hope it doesn't; only Apple have succeeded in doing this so far, but a world where every application developer has to give 30% to the platform feudal lord and suffer arbitary restrictions on development is going to have a lot less innovation.