[qbasic_forever]

Ehh slots have issues too, particularly that if you use them they punch through and totally ignore your shadow DOM to inherit the main body styles. Sometimes you want this behavior and sometimes you don't, but either way you only get it and have no control over the elements passed in the slots. They defeat the whole point or just greatly complicate the idea of encapsulating your element's visuals in one component.

I'm truly skeptical there is much to be gleaned accessibility-wise from templates if JS is disabled. There's no way to know how and where the template was meant to be instantiated in the DOM and accessibility tree without JS.