[PHP-DEV] Inconsistency of empty() and isset() ?

[itrebal]

The following is a direct excerpt from the PHP manual on empty, and isset:
bool *empty* ( mixed var )
bool *isset* ( mixed var [, mixed var [, ...]] )
Is there a reason empty does not allow multiple variables at a time, as
isset? Was there thought behind it, or is it just an inconsistency?