Apple have been pulling this kind of thing for the entire lifetime of iOS at least, which is now at ~15 years. So it's less of an evolution and more of a constant.
Nothing has changed, nothing will change. Apple will make arbitrary and unfair rules that suit it, and people will complain but ultimately stick with Apple, and the cycle will repeat.
Also, buying a Kindle seems like a surefire way to be vendor locked-in, because Amazon is so big, it can afford to not care about anything.
While Kindle is locked in, it seems to be a love child of Amazon and works extremely well. The difference between Kindle and iPhone is that Kindle is a single-purpose device, and iPhone is a general computing platform.
(Snark aside, the Apple is rightfully famous for their tight integration, high-quality user experience, and that basically requires a walled garden. And it's easy to find edge cases.)
And you're forced to because they are not a charity and because they can get away with it. (Both in a legal and market forces aspect.)
For 200-400 bucks you could have a great Android phone.
Not sure where fashion enters into it?
i've been using android phones for the better part of the decade. last year (2019) i've inherited an iphone 6s and the reason i've upgraded this year (to an inherited 8) is that i managed to crack the screen. show me an android phone that has 5 years of support.
Day of reckoning is coming. Monopolistic per se or not I think it's their greed and hubris that will be their downfall (on the matter).