This is a ridiculous take. The iPhone was enabled by unrelated advances in computer hardware miniaturization, it had absolutely nothing to do with Windows' dominance creating "necessity". It was not competing with, and never did, replace Windows. Regulation is needed to ensure that people can compete within a market, not just create an entirely new market as enabled by technological advances which would have happened anyways.
It's a little simplistic, sure, but I mean how much nuance do you expect me to fit into a HN comment? What I left out is Windows Mobile, which was Microsoft's attempt to extend the Windows hegemony to mobile devices. Here are Windows Mobile's US market share numbers, per Wikipedia:
What do you think happened in 2007?