Dan Moren of Six Colors writes about iCloud Keychain in Chrome: “[…] I end up using Chrome a decent amount for sites that Safari doesn’t support well or at all […]”.
It isn’t Safari that doesn’t support the sites, it’s the sites that don’t support Safari. When Mac software breaks because of OS changes, the developer doesn’t say “sorry, macOS doesn’t support my app”. It is on them to make sure their stuff runs on the platform(s) they target.
This whole thing made me think of a good thread I read recently by Rasmus Andersson. In it he says, “The contemporary idea of a web browser is an abstraction layer for technology to allow some document or software to be available to anyone using a web browser. If your website only works in Chrome it’s really not different from say only working on macOS.”