Go ahead, I'll wait.
There are plenty of Linux distributions that use immutable root volumes. They protect the user in a huge number of ways by preventing the system from getting hosed (either by accident or by malicious unauthorized users / malware). Apple made the decision to do this for their users, and it has prevented a HUGE amount of tech support calls, as well as led to millions of happy users with trouble-free computers.
It also hasn't stopped users from installing Chrome and/or Firefox on their Macs, and millions of ordinary users have.
You seem to be ignoring the part where you can't install the Chome and/or Firefox browser engines on iOS and the apps with those names on that platform are just skins over Safari. Notice in particular that the iOS version of "Firefox" can't support extensions.
But hey, maybe some weird shit happened during the clone years that I’m not privy to.
Just an example… and yes, I know the EU ruling but it’s still fitting.
Compare the games console market. Nintendo is allowed to say you have to go through them to sell games for the Switch, ditto Microsoft with the Xbox. Sony doing the same thing with the Playstation is exactly equivalent, but they're approaching the sort of market dominance where it might soon be illegal for them (and them alone) to do that in some markets.
Copyright (e.g. over iOS) and patent (e.g. over iPhone hardware) are explicitly government-granted monopolies. Having that monopoly is allowed on purpose, but that isn't the same as it not existing, and having a government-granted monopoly and leveraging into another market are two quite distinct things.
> Compare the games console market.
Okay, all of the consoles that require you to sell you to sell through their stores shouldn't be able to do that either.
> but they're approaching the sort of market dominance where it might soon be illegal for them (and them alone) to do that in some markets.
Wait, your theory is that a console with ~50% market share has market dominance but Apple with ~60% of US phones doesn't?