This is a classical debate - should we work on our strengths or our weaknesses?
Most societies and cultures teach people to work on weaknesses because they are obvious targets for improvement. As we grow up, people would not ask questions on subjects that we do well, but will only pay attention to failing grades or areas that we don't do well. At work, strengths are considered given, and much attention are given to "areas of opportunities". The system rewards being all rounded and to a certain degree, assumes people have to follow a checklist and are not rewarded for bringing unique strengths on the table.
We all have our very special abilities, those things that we are keenly interested in, derive satisfaction from, and are not surprisingly doing very good at. Some of these strengths are more observable, like communication, while others like strategic thinking and relationship building are more difficult to quantify. But when we are in the "zone", we are not guided by external reward systems but simply what makes us a better person.
Professional athletes will tell you that you must focus on your strength in order to be even competitive. Each activity require a certain level of generic skills, but what distinguishes a very good player and a master is the combination of talent and focused effort on maximizing one's talent. And when you compete at the top level, either having talent or working hard is not sufficient.
From a return on effort standpoint, focusing efforts on improving one's strength also make sense. A high performance team will have people with different strengths working at their own best, while being able to collaborate smoothly. A group of generalists will be challenged every way.