Well, to be fair, I think prohibitively difficult would be more accurate. Just from playing various games I've seen how hard it is to design a good AI, and how easy it can be beak an otherwise good AI with "a minor improvement."
But prohibitively difficult doesn't make it entirely impossible. It just makes it a pain in the ass. I guess I just don't like the word "impossible." It has been my observation that when people say something's impossible, it seems like it's either actually used in place of not wanting to try for some reason or another (difficulty, time, money, etc.), or in place of "I don't believe it." IMO, there are better ways to say something is absurdly difficult.
I am aware that in the realm of mathematics, there are statistical impossiblities, that is, things that are so improbable that they just aren't going to happen in anyone's lifetime, but that's different than claiming a task that is highly difficult can't be done.
All that said, I wasn't trying to take offense. I should have qualified what I said about shutting or slamming the door and I didn't. You called me on it. Fair enough. I apologize.