> The generation of my parents (60s+) is generally not hugely tech savvy. They remember the days of windows XP well - endless viruses, trojans and expensive security software. One of the reasons iPhones are so popular with this group is they let them use the web without fear of dealing with that again.
This is a strange argument, given that Windows XP is more than 20 years old, and the problem already went mostly away 20 years ago, when Service Pack 2 came out.
In any case, the problem has long been a thing from the past. Moreover, I don't see anyone complaining about modern Windows or MacOS computers which aren't locked to an app store. So your explanation doesn't make sense.
I think the correct explanation is much simpler: These people are Apple fans, and fans will, occasionally, be irrationally loyal. Like PlayStation or Nintendo fans.