Seriously, there's even a setting on most pages to change the default font size, so the text renders in a larger font size.
Look on /. ... long pause ... no, it's not here. I've never seen one on any page, much less most pages.
Now, what there IS is a setting in Firefox (and I assume others) where you can set not only the minimum font size but what fonts are used for various kinds of text. Preferences->Content, Fonts&Colors->Advanced. And a small checkbox that says "allow pages to use their own fonts instead of the selections above" which should be unchecked.
I long ago had to set a minimum because of morons who thought that I should be able to read their fancy 3 point font. Where it doesn't always work, I think, is because "size=-1" gets around the limit -- a bug. It's sometimes interesting to undo those setting for a page just to see how awful it looks based on the designer's "vision".
This problem is not limited to web pages. "Art" has taken over the technology world, including many technical magazines and journals. Sidebars that are dark blue text with light blue background, for example, which means you cannot xerox the article even if it was readable. Or background images that have the same lack of contrast for the text.
And while Wired did just fine with the circus layout they adopted, this format does not fit well with all kinds of magazines. "Eye catching" does not equate to "useful" or "readable."