It's mostly free from the OS release cycle now: They have been shipping major web platform features in Safari versions that ship with their minor OS updates. (e.g. macOS 14.2, iOS 17.1) so every ~3 months, which is a nice cadence.

The major OS release cadence only seems to affect major UI revamps which aren't that frequent anyway, so it's not that much of a limitation.

You can now also update Safari independently of macOS, which is nice for IT environments that restrict major macOS updates until they have been approved.

Hopefully in the future they will also allow that for iOS, so that older devices that can't update have some more longevity for web apps (and so that we as web developers don't need to support as many older versions)