It's nice, but it's not quite ready for use yet.

It's not supported on the previous main version of Safari, so everyone following the "last two major versions" of browser support rule can't use them.

Also, it's currently limited to only dialogs and popovers (and custom events, but in those cases you need js anyway).

It'll be more useful once it can control:

- details (open, close, toggle)

- video (play, pause, toggle play state, set seek point, mute, set volume)

- select (open/close widget, set/unset value(s))

- input (open/close widget, set/unset value(s))

- all elements (add/remove/toggle/set a class/attribute)

Yeah, this only gets interesting if they start contemplating native two-way binding, but that still wouldn't cover the vast majority of complex use cases that require computed values.