[LocalPCGuy]

"trying to get sites to render pixel-perfect across various versions of various browsers" - That is a big part of the problem. Now, I have designs I have to get pixel-perfect, so I feel their pain, but when developing your own app, you can opt to not go for pixel-perfection.

I don't believe their statistics, but their target market is much more likely to have multiple browsers and is probably willing to jump into a different browser if IE isn't supported.

But I think it is a dumb move to block IE9+. There is no good reason for it. They didn't give one in their blog post, and I have yet to run into a situation where if I am using web standards that I had many issues with IE9. Nothing I've had to hack around enough that I would want to block it. Seems like either an anti-Microsoft for the sake of being anti-Microsoft or just front-end devs not worth their salt (cause a front-end dev worth their salt wouldn't use user-agent detection to block IE in the first place, they'd use feature detection at least.)