I’ve been teaching design for about 6 years and can tell you categorically, that YES, there are people who do not know about making setting type at different sizes. I’ve seen websites with body text larger than the headings. Sitepoint has readers at many levels of web design and development, not everyone is a born designer and posts like this are written to help people who may be new to design.

I agree with you, the explanation with the examples was a bit sparse, and I’ll certainly take it on board.

A focus on typography and size should tell people about using % and em rather than px;

I disagree. This stuff may be obvious to you, but there are lots of beginning web designers who leap straight into writing CSS styles without planning type size first. This may not be you, but don’t assume that every reader here is as knowledgeable a designer as yourself.

You’ve linked to examples of typography, but why? What should we be looking at on each of those sites? What is it that they do particularly well?

A critique of sites that implement a particular aspect of design well, and why that approach is successful, is definitely good feedback. I’m sure Jennifer will take this on board and fold suggestions like this into future posts. Thanks for taking the time to comment.

A focus on typography and size should tell people about using % and em rather than px; how to avoid the bug in IE6 where setting font-size to small or large makes the type illegibly small or unbelievably large; don’t set the size of body text in px; there’s no need to specify a size at all for body text.

You’ve linked to examples of typography, but why? What should we be looking at on each of those sites? What is it that they do particularly well?

And you might want to check your link to Typetester. When I clicked on the link, it took me to the wrong site. I did a google search and found the site at typetester.org:)