Being a back end developer for the longest time, I never really bothered myself with web browser standards. Not until recently.
I've been into Web 2.0 a lot where the development is more on the front end. I've come to realize how front end web developers are completely at the mercy of web browsers and the stubborn adamant companies who make them.
If you find yourself working on the front end of web development a lot, I encourage you to not only know the standards (yes, we do have standards, that's what the W3C is for) but to also know and understand the quirks of the most popular browsers around.
I guess nobody is perfect, the newer version of Internet Explorer for instance tried to be more standards compliant but have fallen quite short.
Click the title link above to learn about quirks mode and strict mode. May it help you keep your hair on your head and most importantly your sanity.