While I can see some validity in some of the points I can't really say that an NDA is a completely useless tool. I have never dealt with one before so I might not be the ideal candidate to talk about them. Nevertheless I think that if the NDA is reasonable and restricted to the matter at hand, in this case it seems to be some kind of consulting for a new startup, then is OK to use one. After all, wanting to protect a cool new idea is perfectly reasonable and understandable, specially in a highly competitive field.