Inventing stuff that people can use to better their lives is a good example of thing smart, wouldn't you agree? So yeah, dope makes you think, but it makes you think like a dope.
That's only if you completely devalue the arts, which I would object to. There is no question that pot stimulates creativity in the brain, and has inspired greatness in literature, art, music, et al.
I can't speak to engineering & mechanical accomplishments; it's fairly rare that achievers in that field give more personal-related interviews, and even more rare that they would credit something like pot for inspiration....