One of the problems in being a generalist is that there is a tendency for a broad knowledge to be superficial. In order to claim expertise in a subject, I need a lot more depth and detail, which is harder and more time consuming.
For instance. in the review I am doing of the history of psychology, about all I can say is that before about the 19th century, psychology was largely speculative and in the realm of psychology. It did not become scientific, based on measurement and experimentation until the 19th century. I can identify several divisions, but I do not know enough about either the details of psychology or the details of history to make solid connections. I recognize more than I know how to present, but until I can do more than proclaim my ignorance on a topic, I prefer to hold my commentary.