Why not?
Do these new rules include the Android Play Store? Does it include the Apple TV app store? Does it include the Play Store when purchased on a television running Android? Imagine if Mattel creates a new ultra-low cost video games console; should these rules apply to them? What if their console happens to run Android? What if their games console runs Android and the Play Store? What if apps bought on their game store can also run on a phone?
Ultimately it ends up just warping the market and adding yet more complexity into business—and complexity benefits powerful established players over new entrants.
Is this a proven or unproven assumption?
But I must ask: have you ever seen A Government? That's a serious question. Look at any large Government around the world and look for any complex legislation that involves a relatively new business sector or financial instrument. Much of it is obviously terrible, or will turn out to be terrible, or is occasionally so terrible that it creates ripple effects which trigger financial crisis.
Australia launched a new economy-wide GST in 2000 which did many things, and one of them was a massive transformation of the cereal bar/museli bar/granola bar marketplace—changing recipes and picking new market winners—because Governments are terrible at writing legislation.
If there are going to be mandated limits, they should apply to all companies which build hardware and charge platform access fees to software developers.