People didn't catch on that IE was bad until almost a decade later, by then it had finally gotten not bad. These days I don't even have to think about it because my websites work better in it, more often than not, when I open them in it for the first time.
Safari is the one I have to worry about now. It isn't just features, it's page rendering. Not having WebRTC is something all on its own.
But web technology is extremely complex.
If you fall off spec, and then find yourself needing to support those off spec 'features' it holds everyone back for a long time. How long will it be before Safari users find out how frustrating they can be to web developers?