I only mentioned tagged template literals, as they were called out by the article as an unsung hero. Presumably, they are an example of what a good template language looks like. If so, they don't give me hope that we know what a good template language looks like.

The idea of the post seems to be encapsulated in the web components issue and discussion. Agreed that it looks largely about data binding to DOM trees. To paraphrase you, "seems like advanced DOM interpolation in JS." Which, I just can't bring myself to agree that this looks good. Happy to be proven wrong in time.