Gmail does this a lot in the iOS app too - I feel like I'm always telling it to remember my choice of Safari over Chrome. It also links addresses to Google Maps instead of Apple maps without even giving you an option.
iOS is on a completely another level of lockdown, as you can't have third party browsers at all there, only UI wrappers on Apple provided webview widgets.
Even those wrappers can be useful, e.g. to isolate identity management. But even those wrappers are not selectable at the OS level, only within apps that allow you to choose the default browser/wrapper for opening links.
I think it's bad there, too, but it's maybe a slightly different situation: iOS has never pretended to be anything other than a very locked-down walled garden; Windows is supposed to add bit more flexibility. If iOS actually allows other browsers to be installed, then it's made some kind of 'progress', but Windows is moving in the other direction: there's a pretty undesirable average that they both seem to be heading for whereby you can install alternative applications, but the OS will make it much harder for you if you do.
You can install other browsers, but the page rendering must be done by Apple’s iOS system version of WebKit. Basically it’s only good for things like bookmark / history syncing.
Right, and even then, Apple isn't going to help you at all: links from other apps won't open in Firefox, so you jump through hoops to try to get your Firefox bookmark/history syncing support...
Unfortunately people are better at copying Apple on the annoying shit like this than at the stuff they're actually really good at.
I'm referring specifically to the Mail app on iOS. Other apps, e.g. Wire for replacing iMessage and Mail, will let you choose which browser will open links.
Safari doesn't come with several tons of baggage though. It might be unfair, but as a result of IE I find it very difficult to trust a Microsoft browser.