They are, and, if you look around, they're winning: billions of people use Windows, MacOS and desktop Linux, safely, to do all manner of things. Billions of people use the web, which involves all kinds of code from all kinds of places - none of which is held hostage by a single absurdly valuable corporation - and, judging by the continuing success of that platform, I would say it's doing pretty well.
You know what's terrifying? This argument is terrifying. So, you brought up the web … assuming iOS continues to be what it is, and eventually people just stop bothering to make websites: is that okay? Is that what we want?
If we have so little faith in those developers that we believe the last line of defence - the App Store reviewers - are the thing holding us back from disaster, then we definitely should not be using iPhones.
It's really obvious to me which is more secure - a 2 trillion dollar company with vested interest and one of the key selling points, that is privacy; or ... literally anything else.
I absolutely detest this idea of third party app stores. Please tell me why this is a good idea when literally your entire life and its contents are contained in this palm sized device.
Do you really want sideloading of apps that asks average joes for ransomware?
We already have another sandbox - browsers. And you're seeing problems with extensions, popups, .dmg downloads and .exe virus scans, etc. So much so that browsers are constantly fighting against attacks for 20 years.