Why don’t you play as the Academy?

I wouldn't say that the Academy is such a difficult faction to play. Yes, when I started playing Heroes of Might and Magic V, I greatly underestimated this faction and considered it the weakest, but in reality, they have many advantages. They have units with a lot of immunity to various things. They also have various healing units, like golems, and many interesting features through the wizard's mark. So, their start isn't the worst, and this faction is very unpredictable for the opponent, as there are many development options. And in the late game, they are one of the strongest due to their powerful ranged units. A 40-50% initiative bonus, and any faction will lose to them in initiative.
But it's not one of my favorite factions, which is why I play it less often than some other factions.