Tim Cook's head would end up on the chopping block if several billion users suddently left iOS because FB, Instagram and the rest weren't available.
With Google, the userbase is potentially even bigger and some of what they do really is fundamental to most people's experience of the web. Users would certainly revolt.
The same might be true of Fortnite, but despite the fact that we now know most App Store revenue comes from games, Epic is still one of many, regardless of how popular their titles are.