If web developers stop ensuring their sites work in Safari, consumers will be forced to install Chrome. That's not browser choice. An open platform means that CONSUMERS get to choose which browser they use, not web developers.
(And before you say it, consumers can choose Android, where 99.9% of people use Chrome, but apparently that's okay because they "chose" it.)
It's a chicken-and-egg problem. How can you get web developers to test their websites in Safari, when the majority of Mac devs haven't opened Safari in ages? We have the answer already. Safari doesn't compete on it's own merit.
WebKit is a second-class citizen on the web, and we can argue about why that is, but nobody can sincerely deny it. Apple's strategy has been dead in the water for over a decade. iOS lost.
If web developers stop ensuring their sites work in Safari, their sites will still work in Safari because Google ratifies and publishes the web standards that Chrome follows so that Safari and other browsers can follow it too, something that Safari actually does less than Chrome.
Consumers choosing Android isn't a choice of which browser to use, it's choosing which operating system to use. That doesn't sound like you care that consumers get to choose which browser they use, that's letting Apple choose which browser that Apple consumers use then telling them they can choose a different operating system instead.