Why would you make an off-hand attack when you can Shove someone over the ledge or into lava, without any investment in a Feat or Fighting Style? Or drink a potion. Or use a Weapon Skill.
Do people who think this actually play the game very often?
You don't always have a ledge to throw someone off or lava to throw someone into. And even when you do, sometimes it's a bad idea because you want to get the loot.