Let's suppose that one of those online services had been owned by an unrestrained, pre-breakup AT&T (as would have been the case without the government intervention see as unnecessary).
Who here thinks that the open Internet would still have obviously and inevitably won?
They were driven out of business through competition from the open internet.
If the current situation is analogous, then over time we can expect open app stores to drive the closed ones out of business. No need to involve the government.