How do we ultimately identify species? I'm not sure this distinction is relevant as regards the impetus itself existing, so I really have no reason not to yield to your point.
The ability to interbreed does it for me. It kind of boils down to the question of wheather or not there's purpose/goal to evolution though, doesn't it? There's no need for there to be, but the assertion that there isn't is less than palatable, I'll admit.
What twisted purpose or goal could be served by evolution by natural selection? I find the blindness of evolution to be more palatable because at least we can rest assured that this was all just a big mistake. Hilarious beautiful and cruel.