Microsoft definitely takes the blame in keeping it poor for so long but this situation is nothing like Safari which has refused to implement standards that already exist, as well as messing with others in unintuitive ways.
edit: oh and i guess now that i upvoted it it's not grey anymore xD
Safari is not only slow to follow the standards, it is slow to advance the standards. I'd be more likely to believe the spin that Apple just wants to make sure things are done well on the web if it appeared that they were trying as hard to add good, new capabilities to the web platform as they are to add good, new capabilities to iOS.
A engine that isn't Chrome is very essential for keeping the web open
Also essential is for the open web to be competitive with closed alternatives, or the fact that it's open will matter less and less. Apple is quite willing to provide competition for Chrome. It does it with iOS.