I think Safari's priorities closely map Apple's priorities and DNA.
So when it comes to presentation (how text is presented, typography, color spaces, HiDPI, etc, all things that benefit an overall design, user experience) Safari always seems to be way ahead of the rest.
But when it comes to stuff that developers want (stuff that mostly makes devs more happy), it may tend to lag more behind.
That mirrors Apple's general priorities of often prioritizing user experience over dev experience.
And even though I'm a developer, I happen to kind of agree with that prioritization..... on most days :-)
So when it comes to presentation (how text is presented, typography, color spaces, HiDPI, etc, all things that benefit an overall design, user experience) Safari always seems to be way ahead of the rest.
But when it comes to stuff that developers want (stuff that mostly makes devs more happy), it may tend to lag more behind.
That mirrors Apple's general priorities of often prioritizing user experience over dev experience.
And even though I'm a developer, I happen to kind of agree with that prioritization..... on most days :-)