You see, every company has a culture, and culture is much more than slogans. If from the very beginning the employee felt like he couldn't speak up "because it was not in his job description" then there's something deeply wrong about the culture, slogan or not.
The company has divided itself into 2 camps:
1) Design guru - this person does not need to collaborate with anyone (i.e. the mechanical engineer is perfectly competent at designing electronics) because they already know everything. They don't speak to anyone else in the company until they mess something up, at which point they just ask someone else to fix it for them.
2) The other group is perfectly capable of collaborating and working with other people. This group gets things done elegantly and efficiently.
In other words, if group 1 and group 2 were given the same task, group 1 people would end up with a kludge that took twice as long to design than group 2.
So what's the balance? When interviewing job candidates, how do you determine what kind of employee you will be getting? What do you do about the people you already hired?
I have had the problem of good technical people asking me to rewrite my business plan.
One way of dealing with that kind of arrogance is to have upper management that lets each person make the decisions they know the most about. It requires good management, but it means that you can hire people who do not modify their confidence level based on their experience.
Including firing your numpty colleagues and terrible customers: