@vocabRef / @vocabValueRef are mandatory for Field type="entryId"?

The documentation for the field with type entryId says:

The attributes @vocabRef or @vocabValueRef MUST be used to provide context for the entryId value.

Is this really intended? Beside I can’t see any data example using it, this value is probably project-specific in most (or all?) cases, so this restriction should be removed from the docs.