Incorrect, Harmony originally was castable on any mobs outdoors, no matter the level. When PoP came out with large outdoor based raid zones, harmony would have trivialized them, so the level 29 spell Harmony of Nature
http://web.archive.org/web/200405131...d=2317&Page=16 was created to be the "upgrade."
See the original spell comments
http://web.archive.org/web/200407011...ell.asp?Id=863