An "example" binding, by definition implies that values other than those in the bound value set are allowed.  While we do understand that not all readers of the spec are familiar with the definition of the example binding strength, there is a hyperlink to the definition directly in the spec.   We did explore whether publishing changes could be made across the entire FHIR spec to make example bindings more comprehensible to casual readers, but due to R5 timelines, it wasn't something we could do.  That may be something that can happen in the future.