Rightly or wrongly, the Wikimedia Commons community uses protection on pages like "File:Desert.jpg" to enforce meaningful titles.
Upload Wizard should ideally notify the user of this as part of the other checks (title blacklist, title existence, etc.) while the user is typing and surface the protection reason through the UI. At minimum it should enable the user to correct the issue in the final step. Right now it fails in the final step with "[api-error-protectedpage]".