Unless you have super speed and can blitz the opponent before they can blink, punching hard is a terrible argument to use in battle. Especially against a faster opponent. Superman can make good use of his punches because he also moves at the speed of light. Slower opponents can't do anything with physical strength unless they can create shockwaves in air like Hulk's thunderclap, which Tsunade doesn't have. Tsunade also doesn't have infinite durability like the juggernaut, who has complete physical invulnerability.
Tsunade has shown to be damaged pretty bad in the manga, and she doesn't have any solo battle feat. Kimimaro took on Naruto, Lee and Gaara while he was sick. If he wasn't sick, all the 3 kids in that fight would've surely died