This is kind of an over-simplification. Lots of people love certain activities that they don’t have the physical capacity to develop a high degree of skill in. Singing, for example, or playing basketball, or drawing free-hand. On the other hand, not being able to be the singer, the basketball player, or the artist shouldn’t keep those people from being able to be critics, teachers, or otherwise subject matter experts in those fields they can’t perform in.
When it comes to writing, I would have to say yes and no to this article. Perhaps people who love to read and to write don’t have a strong well of creativity, self-discipline and the ability to work alone for long periods of time that would produce a successful screenplay or novel. That doesn’t mean they shouldn’t write. The business world is filled to the brim with positions that require solid communication skills. Or perhaps they do have the creativity and self-discipline, but are still never successful. That could say very little about the quality of their work, and more about the practical realities of earning a living from their work in the present moment. I just read a fascinating article on a screenplay writer who had a movie picked up on Hillary Rodham Clinton’s life who had spent years failing to sell his work. We are all aware of the many artists and writers who became critically acclaimed after their death, and the contemporary writers who are financially successful because of their appeal to the general public, but are not producing meaningful or quality work.