Safari increasingly doesn't follow standards, implements non-standard features, and updates are tied to OS updates so if users do not update their OS (which is free on macOS but not well advertised in the OS itself), they are stuck running an old browser.
Huh. That's changed, then, since previous updates were always tied to the OS. Still not great support, though. Chrome supports back to 10.10, Firefox back to 10.9, Vivaldi back to 10.10, Brave back to 10.10, etc.
