It's that people aren't exactly stretching their imaginations to picture their phone ecosystem going to hell. They've all been there before, and have vivid memories of what they don't want.
They are also not crazy to have different preferences for a phone and for a desktop. Just like you have different preferences when selecting a hotel room vs a house.
The argument is nonsense because Apple decisions are not driven by security but are there to ensure they get a cut of every revenue stream on their platform. If this was just about security there would be a way to verify secure 3rd party payment processing methods - I trust Stripe as much as I trust Apple for example. And you wouldn't be forced to offer the same price on other platforms either.
I don't mind personally I see the value they offer - they make products that are better overall for a large majority of consumers and their ecosystem just works for many use cases - it doesn't fit me particularly well but I see the value proposition.
Pretending that these store policies are driven by security is nonsense, those kinds of arguments tick me off.
Clearly Apple wants to make money. The only argument being made is that some customers choose the walled garden because they want a telephone, not a part-time job keeping the weeds at bay. As you say, that's (a component of) what they are selling, and they do it because it sells (long-term, in their estimation).
The number of customers who chose an iPhone because it only lets them buy apps from Apple is a tiny fraction of the number of people who bought the device as a fashion accessory. What a strange thing to want. It makes little sense to think that Apple is catering to the tiny former group instead of simply extracting as much money as it can out of the latter group.
About a decade ago, I got an iPod Touch, on the basis that it would be a portable computer that I could hack around with. Instead I find that it was entirely locked down, and required permission to install any software. Heck, even the developers kit required a $100 license fee, which was outside of my hobbyist budget at the time. For my own device.
The phone ecosystem has already gone to hell, and Apple paved the way there.
We got a pull request from someone to enable the fonts entitlement, except they couldn't test it because it costed them money to do so. You can see so yourself here: https://help.apple.com/developer-account/#/dev21218dfd6
It's that people aren't exactly stretching their imaginations to picture their phone ecosystem going to hell. They've all been there before, and have vivid memories of what they don't want.
They are also not crazy to have different preferences for a phone and for a desktop. Just like you have different preferences when selecting a hotel room vs a house.