Harmony - Troop Symmetry

Surprisingly, the dragons of Arcat seem to be the closest match in terms of description among the units available in the game. LOL, where's the logic?

The logic is quite simple: the emerald dragons in Heroes 5 inherited traits from their counterparts in Heroes 3, as did many other units, and many players appreciate the continuity of the units.

Add to this the fact that elves have traditionally been strong in aerial units. Making the dragons ground units would essentially turn this faction into a ground-based one. Moreover, unlike the ground-based elves from MtG, this faction in Heroes is not known for having a large number of bulky and powerful creatures to dominate the ground.