It was the most popular because people had to download the others themselves. It was also non-standard, so you often had to make a choice: whether to expend res

It was the most popular because people had to download the others themselves. It was also non-standard, so you often had to make a choice: whether to expend resources to build it for IE because it is most popular and not not worry about the rest, or "do the right thing" and use standards and then write more code to support IE as well.