I found this sign in the restroom at the Sacramento Co-op. It is fairly effective at explaining why their specific audience, co-op members, should not prioritize writing on the vast red canvas. Of course, resources and causes are more important than the snide, silly, ironic, or otherwise confessional comments people need to make.
Plus, we now have social media as a venue to share all of these things.
Writing on bathroom walls is passé.