Architectural coherence is such an important part of software design. I agree with your point completely—you need specialists for deep, specific problems, but you also need people with a view of the entire system.
It also made me think how, typically, the problem with "design by committee" is that it's often a mere collection of specialists, without the necessary generalists (those with an understanding of architectural coherence, system-level thinking) with the power to tie it all together.
I think the reason why many great software projects are created by an individual or a small team, is that coherence and consistent vision across the system.