They were made to be similar because too many people were applying to be contributors for the color without actually wanting to do any contributor work.
Having a color also made it seem like contributors were a special role, which isn't really the case. When MangaDex first started every user was allowed to make edits to the info on title pages, we had only locked it behind user roles when we got vandalized for the first time. It was several months that we had gone vandalism free which was impressive in itself.