I mean the action and target attributes don’t seem to appear anywhere else but the popover api. I’m in favor of HTML dialogs, I just don’t see the point in the trend of making everything into this declarative nightmare it’s becoming when we have onclick=dialog.show() without even quotes.
Script attributes are very often disabled for security reasons.
The declarative actions API is currently only used for popover, but it's been discussed for over a decade to allow SSR of rich content that's interactive before script loading. See also https://developer.chrome.com/blog/command-and-commandfor
For a long time I also pushed back on these interactive APIs because script is a better primitive and every site seems to have quirky requirements. I've come around on it though because there's huge demand for SSR again and businesses are seeing the value in very fast TTI.
I do still think the date picker API is a disaster. Everyone actually needs something much richer than the system date picker. Travel websites want ranges. People want to put dots and day highlights. I wish they'd fix that next.
What I guess this all leads to is that we’re trying to create some kind of DSA that doesn’t have the possibility to hang or crash the way imperative programs must have the ability to if they are to be effective. So it seems like web design is an avalanche of sort of silly css prefixes and selectors and attributes that refer to object ids and everything, when what we might have said instead is that if a script takes more than one second wall clock or something equivalent adjusted to standard then it gets rolled back like a transaction.