This seems like a bit of a trend with Safari. Around big releases Apple will announce how Safari is the best at X, but other times of the year it gets a lot of flack. I assume this is due to Safari’s more traditional release schedule vs other browsers continuously shipping feature updates.
Safari has been releasing a lot more often than it used to. My personal gripe with Safari is how they decided to deal with extensions, forcing every developer through their hellish App Store submission experience.
Cool stuff they're working on tends to take a very long time to reach customers' hands compared to other browsers. Just compare the "stable" and "experimental" graphs on wpt.fyi for Safari.
I can't think of a single good reason why they don't adopt an "evergreen" 4/6-week update model except Not Invented Here syndrome or "it's not Apple-like, we prefer the OS team (and therefore Marketing) dictating our release schedule, users be damned".
It's an own-goal for no reason.