The original point is invalid, although one could say that being good at systematically validating and invalidating assumptions is the sign of a good engineer.
One who doesnt make assumptions at all just wouldnt do anything, though.
I assume that when I press a key on my keyboard, the corresponding character will show up in my code editor. If I couldn't assume that, I doubt I'd see the use of pressing any keys at all.
(For clarity's sake: Not disagreeing at all, just illustrating your point with a reductio ad absurdum example.)
One who doesnt make assumptions at all just wouldnt do anything, though.