No. Some significant differences between those examples and the new proposal:
(1) (most important) Those are all implemented and released. The time to debate how those things might best be handled is long over.
(2) The interactivity of text editing and selection are limited to local state of the control itself. Notably, they don't affect the DOM. pseudo-classes like :hover are effectively DOM operations, but are at least limited to a kind of boolean state flag, which is a lot less complicated and fraught than rendering arbitrary DOM subtrees.
Anyway, as I already mentioned, I'm not arguing against a reactive mechanism built in to the browser. I'm saying if you do it, it should not be a one-off for a single, specific case like <select><button><selectedcontent>, but should instead be a generally applicable mechanism.