The point remains: one cannot bring a fullly independent browser on iOS. Microsoft was successfully sued for much less in the late '90s.

It's a business practice that reduces user choice and freedom, and stifles innovation and competition.

No MS was sued for much more like forcing third party OEMs not to bundle Netscape and forcing them to pay for Windows for all of their PCs whether or not they shipped with Windows.

Yes. Why haven't they been fined for anti-competetive practices already? How can they still force developers to use their only webkit implementation? Is it because people think there are more browsers on iOS, forgetting that actual layouting, rendering and scripting, most of the web browser work is done in the single Apple's implementation? Also online video streaming providers are forced to encode in HEVC, because Apple refuses to support royalty-free VP9 and AV1, despite the fact that even HW implementation of VP9 is available for some time already in many SoCs and Intels (and chips with AV1 are being produced now as well). Microsoft was fined a lot in the past, forced to ask people for app defaults (full-featured alternatives), but Apple seems to have some special treating... and people don't care. As long as Apple says it's "for their security" (which is not true), they believe it. It's sad.

Mostly exists to protect iOS users from all the security issues that browsers always seem to have.

Not that Safari doesn't have security problems, but Apple trusts themselves a lot more than the other companies for security.

I would doubt that Safari is significantly more secure (from a "buffer overflow took over your phone" perspective) than what Chrome could be on iOS.

How do feel about ChromeOS? You can't really bring a fully independent browser there either - you have the Android APIs but they make for a pretty crappy desktop browser experience.

Does it make the device less susceptible to malware?

I don't believe it is even the engine must be WebKit; it is that third parties can't implement a JIT-optimized Javascript engine like JavaScriptCore.

So the browsers are stuck with either abysmal performance numbers due to interpreted javascript, supporting their engine having different javascript behavior on iOS, or shipping a skin over webkit. The skin approach is by far the least amount of engineering.