I would say that philosophy is a skill, like any other. Sure, nothing than an inclination is required to do philosophy, but to do it well requires talent, knowledge, experience, and practice. Obviously if you have no raw talent, you will find it difficult to make up for this defect through experience, knowledge, and practice. A good philosopher needs to be well read in the literature, both to know what has been thought already, as well as to expand their mental openness and exercise their ability to understand ideas. A creative writer or a poet is a better one if they are well read. The same with philosophy. It requires knowledge, obviously, and academic training is the most assured route to this knowledge. It requires experience and practice because it is a skill like any other. So while these things aren't necessary to do philosophy at all, they are largely the means by which one comes to do philosophy well. Thus while to road that leads to destruction is wide, a good philosopher enters through the narrow gate.
(As a personal note, I'm not well read at all, which is my main failing at philosophy.)
(As a personal note, I'm not well read at all, which is my main failing at philosophy.)