Sacred Haven of Debauchery

Well, it depends on who you're currently facing. But there, you need to keep an eye on everyone at once, and you can see them all immediately. If you're spotted in a shooter, you're either dead or your enemy is dead, and that's it; you don't look at them anymore. But here, it's different. They might start surrounding you, or you're fighting, and the enemy retreats while another approaches, or something else happens. It's like a group of thugs surrounding you, and you need to concentrate to avoid missing an attack; otherwise, you're dead. In a shooter, you just shoot immediately without thinking. There's no need to wait.
It's more complex because it's not just about reaction time. In shooters, the fastest player usually wins, but that's not always the case here. I'm saying that the battles in Might and Magic are completely different. They're more complex and interesting.

It feels like you're talking about the single-player mode of Painkiller.

I've seen it, but I wouldn't play such garbage.

Lol. There's actually a balance there, and it depends on skill. A rider can dismount, and others can mount the horse (though on the worst ones). There's even cavalry that shoots. Armor and weapons only play a supporting role because if you don't know how to play, gear won't matter. A naked guy with a club can kill you. Here, anyone can defeat anyone.
In Might and Magic, you need to keep an eye on everyone because almost everyone is always in sight, and you really do wait and watch, rather than looking around the corner for the enemy to appear so you can shoot them in the head