This person lives in a fantasy land. Safari may be on a brief hot streak right now but they have a long and deep history of dragging feet and literally slowing down the entire ecosystem.
I don't think slowing down the (Google-propelled) web standards commitees is the worst thing in the world. The endless rolling release stifles browser competition. I wish we could treat the web as a protocol and say "here, this is all it does and all it will do for the next N years, make the most of it".
In general this would be a good thing, but not the way Safari does it. Why? Well, because eventually, almost everything Safari doesn't implement does get implemented in Safari, and because some of their longer running omissions smell suspiciously like conflicts of interest that hurt the ecosystem. A lot of people are incorrectly under the impression that Safari finally supports WebM and Opus, but it only does so on macOS (and every time I point this out, someone under that impression claims it has changed recently, and it never has; it's like Apple wants you to think it's supported.) Not to mention their "great" influence on the WebGPU standard and any other number of weird omissions and quirks in Safari.
It's annoying that I need Apple hardware to make sure my web applications work in Safari when I basically never need to specifically test Chrome or Firefox.
Funny enough, that might be exactly why web devs want Safari on Windows, optimally with the whole Apple media stack like iTunes is already shipping: to know what their website would do on a Mac without having one.
(Media stack? Yes, I am salty about Opus Ogg support.)