Conforming to standards is important to web developers because it means we can write code once and it will run anywhere that supports those standards. When different browsers behave differently, it means we have to know what those differences are and code around them if we want to ensure our user-base can use our products regardless of platform.
Notice IE sitting way out there on the edge far away from everyone else. This should give non-developers a good idea what the life of a web developer looks like. When I write web applications, I do all my initial testing in Chrome. Chrome has a lot of good developer tools built in that make troubleshooting easier. Once I am done getting everything working right I fire up Firefox and make sure I don't have any missing or broken functionality. I almost never do, so I then up Internet Explorer. Things start getting really interesting at this point. I have to start hunting down each problem, looking through the code, and hunt down what it is about my code that IE doesn't like and begin writing exceptions.