I understand your point, and there’s definitely something to be said for consistency and passion. Writing is definitely an art, but it’s also a craft. My point was not about grammar, it’s about knowing what you’re doing, OR, caring enough to learn how to do what you’re doing.
To your example, the difference between being a writer and being a tennis player is that “professional tennis player” is an acceptable and understood term, while “professional writer” usually refers to stuffy copywriters and is often seen as pretentious or unnecessary. Also, I’m assuming you put in the time and effort to learn how to play tennis. A lot of people who claim to be writers don’t put in the time and effort to learn how to write. Because it’s more than simply stringing words together. Just read a batch of college essays, or, for that matter, a lot of the lower quality posts here on Medium.
It’s an interesting conversation, for sure, and you do have a lot of good points. But there’s been a decline in people putting in work and effort, and I think it’s harmful for humanity as a whole.