Google is effectively shipping a cross-platform “metaplatform”, for which the browser is the trojan horse. Apple is shipping a web browser that only runs on its OS and hardware.
So Webkit is slow or unwilling to implement features that may hinder battery life, user privacy or that simply have better native alternatives. Webkit is actually on the forefront when it comes to CSS features, like the recent has() selector, or JS memory usage and overall page speed.
What I think is a fair criticism is that Safari is generally tied to the OS and gets outdated when the user is unable to upgrade the OS (or oblivious). Evergreen browsers are a revolutionaty concept, not without its drawbacks, but all in all, were very positive to the web.
I use Safari but I would prefer it wasn’t shipped on the same schedule as the OS. I understand why (I think) but I’d rather have more frequent updates, even if only every 3 months or so.
That’s a problem with most Apple apps. Bug in Mail? Better hope it gets fixed in the next iOS or MacOS point release. Because the fix isn’t coming out earlier.
Safari Developer Preview is stable and available out of sync with the OS.
It does make sense that it is shipped with the OS since Safari is just a wrapper around the OS WebKit library which is used across many apps and services.
A browser is so fundamental to modern computing that if you can't run the latest version, you might as well have a paper weight. You can run mail, office, games, all in the browser if the native alternatives fail you.
Chrome still supporting High Sierra is what makes old Macs usable.
How many of those "actual HTML standards" in the past 10 years are actual standards and not "whatever Google scribbled on a napkin and pretended it was a standard"?