Can't enchant items with constant effect on self magic effects for non-player character

Morrowind allows enchanting items with the effects meant for non-player, those effects are useful because the items can be given to the actors (for example companions or merchants) and they would work on them.

This giving other actor items enchanted with constant effect stuff already works with other effects.

Note Morrowind does allow them for magic effects that can be cast on objects too (open/lock), but obviously that has no use.