RSRs [1] are sort of not this though. They’re still a bit weird, but can contain updates for WebKit and/or Safari in a very small update that installs very quickly. Also worth noting that WebKit is buried pretty deep in macOS (as it underpins a lot more than just Safari) so isn’t as easy to patch by itself.

[1] https://support.apple.com/en-mk/guide/deployment/dep93ff7ea7...