A poorly designed ability can have multiple problems. Those problems need not be intertwined in a way that makes them all simultaneously relevant to any given example.Where you really didn't manage to say that clearly in your previous two replies.
You were also focusing on this being a problem with a specific scenario of players using this on an unarmed attack while being shackled as prisoners, whereas it seems that what you're actually objecting to is the way that paladins, battle masters, monks and probably a few other classes have been functioning since 5e was released.
@James Gasik 2014 phb's smite is also badly designed
Video set to shield spell section's timestamp