there are also false moorish idols or schooling bannerfish. I dont personally think the fish are nearly identical though, colors are a bit different and much finer scales on moorish idol. The face of a moorish as well is quite unique imo for most fish, making it more interesting. I think most came from hawaii anyway so we should see a price increase as well as lower stocks in the future. Cool fish but not worth the risk of keeping them for it just to perish.
I suspect it's in part an ego thing. I've had friends get Moorish Idols and proudly tell me they've got them to eat but give it time and they don't have it anymore. The Heniochus acuminatus does look very similar and I've had people mistake them for Moorish Idols (a couple times knowing my position on keeping them hypocracy on my part has been suggested). I haven't had issues with Heniochus acuminatus eating corals and they do very well with just pellets but I haven't had much luck with the other heniochus species adjust to accepting pellets and requiring frozen foods.