[bendavis381]

This is incorrect. Safari 12 shipped with support for macOS 10.12 and 10.13 [1].

[1] - https://developer.apple.com/safari/whats-new/

[apocalyptic0n3]

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.