Firefox extensions don’t work on iOS. Tor Browser can’t publish to the App Store. How is this different?
Re 1, the idea that an end user OS would be anything other than deficient if it wasn’t bundled with a web browser seems quaint. And honestly it was dubious at the time.
What's the rationale for that? If I were to take a wild guess, I'd say it's for security. Apple trusts their own implementation but they wouldn't want to be forced to review the security of other implementations because the code is huge and complex and it's so critical to user security. But I'd like to know if they've given an official reason.