It is different when you write for journals.

• You can't write about anything you want - you can only write about what a particular journal is interested in. Each journal publishes papers on an extremely limited range of subjects.
• You can't write for whoever you want: your primary readership is defined for you.
• You can't choose your own style of writing: it is set by established standards, rules and conventions.
• You can't chose you own layout or format: these are determined by the publisher and designed to make every paper look the same.