Good programming practices make your work easier, and I find this “flows over” into other stuff that you do, like markup, configuration files, etc. That people use obsolete HTML in examples could be lack of knowledge of the latest and greatest. In practice, I think that the people who provide the examples just try to convey some information particular to the question. Just showing the essence of some technique almost never requires all the bells and whistles of CSS, for example.

So the people using the obsolete methods in examples are on the safe (works everywhere) and efficient (just the basics) side. This may not be innovative, but is (IMO) smart ;-)

Arjen