I agree that we should try to be more positive. But for every useful startup there are dozens of quibis, juiceros and many others you mostly don't hear about, but would recognize as dead-ends if you paid attention.

So where do you draw the line? When something looks like BS vs. simply unusual/innovative. PG said that most good startup ideas are counterintuitive otherwise they would have been done a long time ago. But there are also a lot of counterintuitive ideas not worth doing.