Except that's not what happens. My mom gets spammy magazine article notifications which I offered to help her get rid of, but she actually wants them for some reason.
https://www.pcmag.com/news/study-reveals-googles-play-store-...
https://www.zdnet.com/article/over-half-a-million-users-been...
https://www.tripwire.com/state-of-security/more-malware-infe...
https://www.darkreading.com/attacks-breaches/malicious-apps-...
https://lifehacker.com/great-now-the-apple-app-store-has-mal...
Etc..there were some studies posted about this too
The befuddled kind grandmothers of the world can just not install/sideload alt stores.
The most common way the elderly get scammed is over voice telephone conversations. Would you suggest we disable the ability to speak over the phone to “protect” them as well?
Their computers are a mess. No matter what pro-active measures I take, every time I get involved, they have a bunch of nonsense installed doing who-knows-what. Random apps, most of which are running all the time, slogging down the system. The younger folks have different game-stores, or other similar things, all running in the background. The computers are slower than mud.
Their phones are all fine. They may download crap, but I know it is almost impossible for it to mess things up outside of that individual app.
I'm not saying this to completely defend Apple - I honestly don't know which side of the App Store/sideloading debate I fall on. I'm just pointing out that there are huge benefits, particularly for the general population of non-techincal users, to Apple remaining as a gatekeeper (albeit obviously a quite imperfect one).