[stult]

I don't necessarily disagree with your conclusion but your analysis is an oversimplification. It's possible reading broadly across domains results in deeper individual domain expertise by enabling cross-fertilization between the domains. So the relationship between depth and breadth isn't necessarily inverse or linear.

Take the recent solution to the Kadison-Singer problem. A group of relative outsiders with comparatively little mathematics expertise solved a long standing problem using techniques from their own field, computer science. The depth they achieved in math exceeded that of people who focused solely on the math. And similarly they achieved more in their own field by tackling problems from other fields.

Obviously there's a very tight conceptual relationship between those two fields even if that isn't always the case institutionally. But I think you can easily find examples where knowledge from dramatically different domains contributed to some paradigm shift, breakthrough, or other significant achievement.