It's all supply and demand. If you are a top grad at a top program in CS, there tends to be enough faculty spots. Some day far in the future when funding dries

It's all supply and demand. If you are a top grad at a top program in CS, there tends to be enough faculty spots. Some day far in the future when funding dries up and the field gets older, I assume there will be fewer open spots vs. recent PhDs, so more and more grads will have to do extended postdocs to prove themselves worthy of a faculty position.