Web/DTP is not the same thing at all. DTP is static. The web is dynamic.
You can envision some paragraphs of text in a blog post being re-flown but the web is more than that. What about interactive text? Text in SVG? Multi-language text in the same paragraph? Various stacks of text in varying z-indexes, css-3 animated? Text manipulated with Ajax? In a mobile browser AND in the desktop. Not so easy anymore when you have to cover all of those --and possibly in a W3C or HTML5 sanctioned way, compatible with concepts like "overflow" and all.
You can envision some paragraphs of text in a blog post being re-flown but the web is more than that. What about interactive text? Text in SVG? Multi-language text in the same paragraph? Various stacks of text in varying z-indexes, css-3 animated? Text manipulated with Ajax? In a mobile browser AND in the desktop. Not so easy anymore when you have to cover all of those --and possibly in a W3C or HTML5 sanctioned way, compatible with concepts like "overflow" and all.