Considering the whole of a large market share mobile computing OS a private market, and not subject to competitive pressures, leads to monopolistic capture similar to what utilities could achieve without regulation. Why not just move to another neighborhood if you don't like your electric bill? Well then you're subject to the monopoly on that side of the fence just the same. Illusion of choice/competition
Competitive markets are what drive down margins, thus feed those margin savings back into consumer's pockets. Cheaper goods+services are what enriches broader society and are a net positive in my view.
Some states solve the natural monopoly problem with utilities by allowing consumers to choose the energy provider separately from the utility itself. e.g making the power provider a competitive market.
If Apple's app store and browser are the best, and people prefer them, they can continue to use them. But they will have other choices in the future