[0] https://www.theregister.com/2021/10/22/safari_risks_becoming...
[1] https://appleinsider.com/articles/22/06/10/uk-antitrust-agen...
I have had a design that broke only on Safari, and I would be at my wit end on how to fix it if I didn't have a Mac on hand.
Even Microsoft still provide VM with IE8 [0] for testing purpose.
0: https://developer.microsoft.com/en-us/microsoft-edge/tools/v...
I use BrowserStack for it; for just one issue a trail account is enough, if you use it for an open source project you can request free access, and for a business it's relatively cheap.
I've got a pro account for a few of my open source projects; I don't often use it, but have on occasion (for things like you describe, and I don't have a Mac on hand).
Some time in the last couple of years, it needed an OS update that took a couple of resident Apple experts to get through.
Edit: oh, I should add:
The main data from your first source is out-of-date... Here's the dashboard today: https://wpt.fyi/compat2021?feature=summary&stable
Your second source is more of an argument to keep Safari around. If the Chrome/Safari duopoly on mobile is a problem, getting rid of Safari makes it worse.
Webkit is doing pretty good on https://wpt.fyi/interop-2022 so I'm not sure why Safari should be retired.