Would it have made any difference if Xhaka had thrown himself at the player and pulled him down with his arms instead of his feet? Would that have been a red card? I think not. Daft foul but not a red.
If he did that then that is a definite yellow. Its because he went with his legs that i guess you could construe it as dangerous and red.
I think the vast majority of us still live in the past, try do a refs course online and see the answers to some of the questions/rules, they will boggle the mind