Yep, it does make you wonder, doesn't it?

I thought ... tiresome browser-compatibility fixes were a thing of the past

Not by a long shot. One thing to keep in mind are browser half-lives. IE's decay rate, in particular, is horrible. IE 6 is still a problem in some sectors, and IE 7 & 8 still linger just as much, if not more. IE 9 is a huge step in the right direction, but still, more advanced features such as support for local databases, ES 5 strict, web sockets, and web workers, won't land until IE 10. The same is even true for lesser features that other browsers have had for years, like text shadow.