I see Ahimelek win battles very often around here, and without needing 3+ other cards to make him work.
But you need at least 1 other card (2 if you want better chances of it working) just to make him work. Ishmaiah only needs 1 of 3, and thats only if a hard counter is present.
Uhh no, you can still RA with Ahimilek with only him out, and that still gets you protection from capture.
Additionally in order for Ishmiah to be really valuable you need several other banding cards to get into battle, this adds up to a lot more cards needed for Ishmiah to work right than Ahimilek needs to work right.