Somewhat. Microsoft reverse-engineered a lot of Netscape's rendering quirks, as well as adding their own. Being quite liberal it what it accepted certainly didn't hurt IE adoption. (And a lot of these things are now in black&white in the HTML5 spec).
"[W]hy do we have an <img> element? Why not an <icon> element? Or an <include> element? Why not a hyperlink with an include attribute, or some combination of rel values? Why an <img> element? Quite simply, because Marc Andreessen shipped one, and shipping code wins."
