I agree with your response that as an engineer you could potential build something with enough time, but I think its important to note there is an important aspect in addition to that optimism. It is an engineers job to also be pessimistic, pointing out huge flaws and explaining that it might not be exactly what you want to do.

Engineering is always a trade off and this issue is no different, when to be pessimistic, and when to be optimistic.

Enjoy you blog and I am enjoying you book, keep it up