In DoS1, I remember being able to basically just leave the rest of my team behind because my main (a mage) could clear the entire thing himself. Most fights ended after my first turn.
Ofc. Redused CD. Cast CC or dmg -> Stealth -> repeat -> gg
Rogue, Warrior and Archer could do the same
EDIT: I'm not going to call it a mechanic because mechanics are just elements of gameplay and they don't have an inherent problem, the problem is how they work with, and compared to, the other mechanics.
Elements of gameplay like armor system, resists system, CC system, dmg system, builds variety, difficulty system, economy, quest system (doing y before x), attribute system, schools synergy system and all all all have a problems. So i cant understand what are u talking about. Sorry
Maybe after 25 years of gaming i want to much from the game of 2017... but no.