Limitations

There are infinite ways to write a poem.  A given literary culture, though, will settle on a few viable  options. Within these options, some will seem too old-fashioned; others too strange for mainstream consumption; others just in the middle. But what will be missing are all the possibilities people just have not thought of.

Most people are not very original. At best, they will put their own personal spin on an option that is similar to what other people have done.

The literary culture is correct, in its own way. Infinite possibilities are too endless to do anybody any good. Even in a fragmented literary culture like ours, what little cohesion that does exist arises because people get together to limit the possibilities in a few major groupings. And the reasons why people say you have to write in a certain way make sense, up to a point. If you want to do something completely different, people will give you very good reasons why it is a bad idea.

What people mean by good or bad is mostly a question of conformity to a given period style. The best predictor of what poem in a magazine will be like are the other poems in the same magazine. This is also why writing programs lead to more uniformity of style: you are in a group of people with a teacher, and the goal is to be published in that magazine.  The writing workshop will reinforce the most prevalent ideas about writing.