In the 1990 decade,we got the imagemap. Some people decided to build an entire Web page as a giant JPEG backed by an imagemap for links. Mercifully, those are all gone, I think.
In the 2000 decade, we got Flash. Plenty of people decided that their whole site would be a Flash application. Some of these are still around and only now realizing their error.
In the 2010 decade, we got AJAX. As could be expected, we are now seeing sites entirely build as a JavaScript application. Which is just as wrong.