The "proper elements" seem to change every two or three of years. For people getting real work done, especially if there's a lot of legacy markup involved, it can be very challenging to stay up-to-date with what the talking heads have decided is the "proper" way of doing things.
Just look at the <b> tag. 10 years ago, we used it frequently. Five years ago, we were told NEVER to use it, and to use CSS instead. These days we're told it's okay to use again, because now under HTML5 it has new semantic meaning. Five years from now, by the time people have used it throughout their markup again, the attitude will change and it'll once more be verboten.
So? There is a new version of the spec, go read it, learn how it's supposed to work, then decide which parts you want to implement. Point is, there is not a single HTML5 tag in 4chan's markup as far as I could see. They're completely missing the point.
It's only the OCD CSS designers who treat every superfluous div and span as a stain upon their work. The rest of us happily use the new meaningful HTML5 structure where appropriate, and keep sprinkling on divs/spans to help guide the layout and style.
And FYI, the <b> tag wasn't supposed to be replaced by CSS, it was supposed to be replaced by <strong> in cases where you wanted to highlight a span in text. Because the act of highlighting text shouldn't be coupled to what it looks like. Unfortunately, most people can't think in semantic terms and still write web content like it's MS Word. That's why HTML is such a complex beast: because we humans constantly give ourselves too much credit, and ultimately, the web is an enormous hack job achieved through minimum effort.
Just look at the <b> tag. 10 years ago, we used it frequently. Five years ago, we were told NEVER to use it, and to use CSS instead. These days we're told it's okay to use again, because now under HTML5 it has new semantic meaning. Five years from now, by the time people have used it throughout their markup again, the attitude will change and it'll once more be verboten.