No they were not setting standards. They were in fact breaking them. Their own standards were not disclosed, forcing competitors to actually have to reverse engineer them in order to try to have a chance at compatibility. The whole reason for the lack of uniformity was Microsoft fucking with the standards!

Secondly, the competitors did not have a significant market share. Thirdly, it’s funny that you mention in the context of a developer, given that they all complain mightily, even to this day, about having to support the festering pile of IE versions still around. Still, this won’t stop you telling, so you go do your thing elsewhere please.