I don't really think his qualifications have much of a bearing on that - you could easily think of knowledge as a function of time and effort, which are certainly limited and finite resources for everyone, so the analogy still holds.
I subscribe to this as well, but I still think Doyle has a point. Sherlock wasn't talking about neural biology, but about the structure of the conscious mind. In practice, the advantage of an "efficient brain" might not be very important compared to having focus in one' thinking.
In other words, the problem is not that we have too many pathways in the brain, rather that we spend too many cycles traveling down redundant ones. Let this allegory warn us to accept the scarcity of attention.
The more efficient it is, but as an economist, I'd say those are two different things.
Your efficiency per unit resource may increase, but your total resources are still finite. Therefore, unless your efficiency increases asymptotically fast enough that the integral diverges (ie, infinite area), your total end product will still be finite. And I have a hard time believing that efficiency would increase that quickly.
