You should always follow the rules of the instance, of course. But if you want to do something that is not within the rules of the instance, you can always set up your own instance or find another instance where this is allowed. Even if a community (like a subreddit) on an instance thinks a certain, way, they can’t conflict with the instance rules.
Creators would probably have to try sharing things in a way that users would not consider it an add. But those lines would be quite blurry, without any clarification from the instance moderators.