_{Note that I (try) to mark up as semantically as possible because I like they way it looks and feels, but not because I'm aware of any other stunning advantages. The point of my question is to be able to educate others}

Well, I've seen a lot of articles and tutorials which often state "Let's mark this up in the most semantic possible way".

But a strange thought came to me, why?

Why would one need (or want) to bother with the specific elements which convey the correct semantic meaning? Specifically, I'm referring to the new HTML5 elements, such as <time>, <output>, or <address>. Especially, if the page "works" (it renders nicely in all browsers).

Why would I want to use elements like <time> or <address>, where nothing at all (or at the worst case, a generic <span>) works just as nicely?

I'm asking this because I'm seeing a multitude of (very popular) websites (this one included) which does not follow these so-called best practices.