There may be computer systems that do their individual tricks well enough, but when you compose them together, they don't do so well. For instance, we have moderately good textual language translation, and we have moderately good speech-to-text software, but if you try to use them together, those success percentages - say, 60% each - need to be multiplied together, and suddenly you only get a 36% total success rate. All the pieces for some really cool software are out there right now, but the overall effect of composing them together is less impressive than it could be.
Mokalus of Borg
PS - It can give you ideas, though.
PPS - And it can be useful for prototyping.