I don't think there's a good case to be made for Safari outside of Apple devices.
> Apple's offering, Safari, currently holds 18.34% of the internet browser market, with an estimated 844 million people using it in 2021. Safari also makes up 23.78% of all mobile device browsers worldwide, which is high considering Apple holds 26.35% of the mobile vendor market. https://backlinko.com/browser-market-share
Those numbers seem relevant to me.
I mean nobody super exciting, but Steam uses it for their software, Adobe CSS uses some of it, etc.
It's more than an Apple thing.
[Edit]: Sorry, nobody outside Apple uses Safari, but a lot of people outside of Apple use WebKit, Safari's engine.
It is also primarily there to render Steam and steampowered.com so not very relevant to keeping web standards in check.
So that's why.