As a journalist, you probably haven't had to deal with the unbelievable pain and anguish of attempting to support IE over the past decade.  They have, and their fed up. They aren't alone, it's a common web developer perspective.

These guys didn't test IE (6,7,8,9, and 10), and then decide that it was too much trouble so they'd better blacklist it.  They simply didn't test it at all, and put up a blacklist so that the 1% of their potential visitors using IE wouldn't get the wrong idea.

Like Rey says, Microsoft has built up a lot of bad blood between the itself and web developers.  They may be trying to turn over a new leaf with IE 10, but because they lack an auto-update policy 6,7,8, and 9 will still be with us until 2025.

Incidentally, unlike Rey, I wouldn't lump IE 9 and 10 together. IE 9 doesn't support CSS3 as well as Chrome or Firefox.  For examples, visit caniuse.com.