Because With Shuusi he cant cut a clifff with the force he applies while trying to cut down a tree.
If Zoro uses haki he can.
You are forgetting that what he did wasn't a casual swing. The was huffing and puffing from all the haki the sword was draining from him
That wasn't Zoro's physical force that cut the cliff. It was his haki.
So when Zoro uses the same haki with Shusui he can do the same.
People forget that Zoro's cut things HUNDREDS OF TIMES bigger than that cliff by just swinging his swords with haki back in dressrosa. He casually swang both Sandai and Shusui and was Slicing up ALL OF PICA.
So no, if Zoro used haki on any other sword he would've done the same thing. Enma is special because Zoro DID NOT want to use haki yet the sword forced him to