Comment by spankalee

This is simply not true, both in how it worked and why it was rejected.

HTML Imports didn't need JS to work: they used link tags and could transitively import HTML files without any JS.

You only needed JS because the wasn't anything you could do with the HTML yet because declarative custom elements don't exist yet.

HTML Imports were rejected because they created a parallel module graph to the JS module graph.

I think they could have been made to share the same graph, but that's basically what HTML modules are anyway.