The argument is that, for most people, letting them do what they want with something they don’t really understand is not a good idea. In this case it also creates a support headache for Apple. At first, they kind of tacitly accepted that jailbreaking was just going to happen and didn’t really actively fight it other than to close exploits used to root devices. As more and more people did it, for the reasons outlined above, more people wound up with bricked, or otherwise malfunctioning iPhones. When they went to Apple to fix it, at first there was an effort to help (you know, to retain customers), but they had voided their warranty. Because of that, Apple wasn’t really interested in spending lots of time troubleshooting something when they didn’t really know the full status of the OS (b/c there were multiple ways to jailbreak, and most of the fools taking their rooted phones to support didn’t understand enough to tell them what all was done beyond, “my kid’s friend said this would be cool”). Eventually Apple washed their hands of the whole thing and started refusing any support for rooted phones. That part, I have no problem with. They also started actively working to stop folks jailbreaking. That part, I thought, was too much. Just tell them they void the warranty by jailbreaking and refuse support. They dug their hole.

FWIW, I use an iPhone for personal use and android (Pixels) for work.

The way I see it, when I buy a phone, just like a pc, I should be allowed to do what I want with it.

Apple disagrees hard with that, they think they are the only ones who should ever have full access. It's easy to see why: If you have root access, you can get rid of their tracking and other data collection and avoid the ads that are shown in built-in apps like the app store.

Some of the jailbreaks could be performed simply by visiting a specific website. Bugs in the web browser in earlier versions of iOS would trigger something known as a buffer overflow. A very specially crafted web request could target a buffer overflow bug that could cause arbitrary code to be executed within iOS. It would require a lot of trial and error to figure out how to craft appropriate commands.

You rely on security exploits that grant access to low level stuff, which then allows for jailbreak. As security vulnerabilities get more and more discovered and fixed there’s just less opportunities to have root access.

Why would Apple prevent this Capitalism, that’s why. It’s their way or no way.

I guess I should introduce you to Louis Rossman's YouTube channel...

This is the reason why I will never buy an iphone, way too limited. On android I don't even need root access to install alternative app stores und custom apps.