One can disagree without being disagreeable. “From my experience, this approach will have the following downsides…” is disagreeing. “Only an idiot would suggest that approach” is being disagreeable.
Too many engineers take the 2nd approach, and then tell themselves that everyone else is the problem when they get labeled as “disagreeable”. At best, they mean well but are sorely lacking in social skills. At worst, the cruelty is the point, and “I’m just telling it like it is” is their attempt at gaslighting others.
