Telling someone why their idea is worthless and will fail is, while also useful, pretty negative. Telling someone how they can change their idea and informing t

Telling someone why their idea is worthless and will fail is, while also useful, pretty negative. Telling someone how they can change their idea and informing them of the obstacles they'll need to overcome and being nice about is more useful. The first seems more haterish than the second. It's my impression the guy wrote a somewhat scathing email.