HTML isn't PostScript. Until good tools exist, web designers will continue to be used as human shields in the browser wars, with our customers being the big losers as they pay us to make two separate versions of everything and serve HTML out of custom databases. Web pages are about communication, design is about communication. Over many years the publishing world has developed a 'visual language' which encapsulates sets of unspoken rules, e.g serif fonts for blocks of text, san-serif for headlines, short line length, the importance of white space, different styles for different functions, techniques for drawing the readers eye into a story. It took a while for web designers to realise that all the accumulated knowledge of 'physical' publishing wasn't obsolete once the web came along.
Web pages are after all still about communication.
This can all be done with a bit of html trickery. And that's all to the good. Publishers use these techniques because they work. It's easier for the reader to get the information from the document into the brain via the eyes. But every trick used to apply these techniques to a web document can make the resulting page more inaccessible.