«فَلِكَوْنِهِمَا نِسْبِيَّيْنِ»
Because the two are relative notions.
Concision and expansion are not absolute magnitudes. One utterance may be shorter than a second and longer than a third. A standard is needed before “less” and “more” can be judged.
Yet this comparison remains tied to successful communication. An utterance that loses essential meaning cannot earn the title of good concision merely because it contains fewer words.