Furthermore, Internet Explorer was _not_ dominant when development of the Opera browser began. I'm not even sure wheter Internet Explorer _Existed_ at the time the development started. IE had a minimal marketshare when Opera was released, and Netscape was the Major competitor.
And, the relatively low marketshare. Well, heh, its kinda difficult to find out that a person is running Opera, if he doesdn't configure it to identify itself as it specifically. Opera defaults to identifying itself as Microsoft Internet Explorer for Windows. You can see the amount of people that _specifically_ has changed the settings, but you cannot see how many actually uses it.