I understand the point you're making, but the bigger reason that <dialog> isn't being used is because it's still locked behind a feature flag in Firefox since they haven't fully implemented it. For a recent project I was actually looking forward to using using it and would be more than happy to add the bit of JS necessary to toggle it, but ended up having to reinvent the wheel and make my own modal component.
If all we needed was a bit of JS to wire up state between HTML elements like <dialog> and <details> I think we would still be in a great place, even if we didn't have native data-binding. The bigger issue IMO is that in many cases native elements can't be used either because they fall short of the desired UX and can't be extended/enhanced (e.g. <select multiple>), or browser support isn't widespread enough (e.g. <details>).
If all we needed was a bit of JS to wire up state between HTML elements like <dialog> and <details> I think we would still be in a great place, even if we didn't have native data-binding. The bigger issue IMO is that in many cases native elements can't be used either because they fall short of the desired UX and can't be extended/enhanced (e.g. <select multiple>), or browser support isn't widespread enough (e.g. <details>).