Sony explicitly didn't allow for cross-play until 2 years ago [https://kotaku.com/sony-is-finally-allowing-cross-play-on-th...], even though it was technically possible before then [https://www.engadget.com/2017-06-24-rocket-league-cross-netw...]. In fact, the only reason Sony opened up to cross-play is due to pressure to stay competitive with rival platform Xbox. This was a take-it-or-leave it situation, but Sony was too big to leave. Nothing changed until Sony caved to social pressure.
If the argument is that Apple is a unique kind of device that Apple has a monopoly over, it would hard to argue that Sony and Microsoft don't enjoy the same monopoly powers. On the other hand, if argument is that it's easy enough to switch from Playstation to Xbox, then how is that different from buying a new phone?
In fact, I would bet that Epic sued Apple not because it's more monopolistic, but because they want to set a legal precedent that they can then apply to Playstation, Xbox and Switch, without threatening Epic's core business on consoles.