Heroes of sword or magic?

It doesn't quite align with the fact that in Heroes of Might and Magic III, spells like "Chain Lightning" (Solmyr) and "Meteor Shower" (Aislinn) are prohibited in battles without a fully upgraded Guild Hall 4.

That's complete nonsense! If we're not talking about tiny maps, offensive magic (like lightning) is simply not effective (even if it has +20 power, but attack and defense are only +5). If the armies are equal, a warrior with attack and defense exceeding the mage's by 10, and with +5 strength and knowledge, can much more effectively use mass shield, bless (not to mention slowing or speeding up) to defeat the mage! By the way, I think general slowing and speeding up is much more of a cheat than chain lightning or meteor shower.