Given the apple v epic ruling about in payment commision outside the app store, I don't understand this. I assume Google would get the same ruling if they tried what apple did, so why bother with walling off if you can't get paid?

At least with 3p app stores they could have Gpay if the app developer wanted to, but now they will be pissed and can't build a 3p app anyway since users can't install it via 3p app stores.