So. Let me get this straight.
The PHB is made less functional for players to make it easier for the DM to go rummaging through the PHB whenever an abridged monster statblock without the information actually needed to use the monster forces the DM to reach for the PHB.
It's not just monsters who get spellcasting like that. Look at Drow, Tieflings. Look at Shadows and Elements monks. They get spells without spell tables specifying levels.