Aren't you just describing... competition?
If Apple's browser product is superior, users will use it. If those users want a feature Chrome has, Apple can either implement the feature or ignore it. That's no different than things are today, if you wanted to avoid a Chrome hegemony then we should have invested in a better cross-platform delivery mechanism than Electron. We didn't get one.
Apple's support to WebKit and Safari is entirely compulsory. I agree that it's a positive impact on the web as a Firefox user, but I'd also argue Apple's ends did not justify their means. The development of Safari is very distinctly neglected to increase demand for native (read: taxable) APIs.