I see the resident Apple bashers are already warming up their cannons firing a few rounds.

But perhaps we need to take a step back here for a moment....

First you need to consider the security and general platform profile of iOS which is fundamentally different from MacOS. Running MacOS would greatly weaken the iOS security profile of Apple mobile devices, and you have to remember that the devices are not just used by consumers but they are used widely in the corporate world too. iOS loaded with corporate apps is a much more attractive security footprint for corporate IT departments. Personally speaking, I very much like the tightened security footprint of iOS. I wouldn't want to run full-blown MacOS on my phone or tablet, even if I could !

Second, prior to Apple silicon, non-mobile hardware ran on Intel. So Apple were justifiably technically constrained by that fact. However, if you observe Apple today though, you can see MacOS on Apple Silicon allows you to install iPhone/iPad apps simply by downloading them from the App store as you would on an Apple mobile device. I would argue therefore that with time, we may see further blurring of boundaries in both directions.