They are using it as a proxy for "people with low technical skills" (which is a specious argument since it was a friend of my parents who got me into programming and he remains one of the best I've ever known) and making the usual argument that we should limit control of our devices to make it safe for them.

I actually don't have (much) of an issue with walled garden approaches as long as the wall has a gate that is easily opened, give me an OS level toggle with a warning of "Here be dragons" and I can live with it - it's not ideal but it's not a terrible trade off.

It's something Android has had previously (but they seem to be trying to lock that gate) and iOS less so.

I think GP means "parents" as a class of not so tech savvy people in your family who need to be protected from naively installing malware.

and the purported purpose of notarization is "blessing" trustworthy software.