The iPad runs iOS, which I suppose is what they meant. Windows ARM is less locked down than Windows S. iOS is still a walled-garden with a few holes here and there.

The second part of your question is key though "why most people should care." They obviously don't. It "just works" and generally keeps them from doing insecure shit. Want to buy hardware from someone else? Tough shit! Why would you anyway? You've got money to burn and no desire to write code that runs on your box without a second "real" computer. Buy some more lightning cables while you're at it. Don't forget to mention green bubbles next time you message an Android peasant.

I said that last part pretty snarky, but you're not wrong about most people not caring. That's their audience and they've nailed it.