IE was technically garbage and people eagerly wanted to get away from it as it broke sites.
Sites are now mostly built and tested on Chrome. Firefox breaks sites.
Sites are now mostly built and tested on Chrome. Firefox breaks sites.
Also, IE wasn't technically garbage. There were a few, specific things wrong with it. Its main issue was that it implemented web features idiosyncratically, and Microsoft didn't document it, so you had to learn all of IE's "quirks" through trial and error: but apart from being undocumented, few of IE's idiosyncrasies were actually bugs. Its box model, for example, was arguably superior to the official W3C recommendation.
But the situation is nothing like when IE was alive. Webdevelopment is much more pleasant now.
If I had to pick a black sheep now, I would say it's Safari, simply because the updates are tied in with OS updates. That's a shame.