> But as much as I hate to admit it, it is very difficult to build something functional today with plain HTML and no/minimal JS.

I would certainly agree that using a little JS can get you further than just HTML. But I think that a plain HTML page is far more pleasant to use (and thus, functional) than the JS monstrosities that dominate the Web today. There's a reason people use the NoScript addon: because a whole lot of website designers use JS in ways that make the experience a ton worse for the user.