I had no idea... can’t recall ever pitching a tent on a ‘tent pad.’
It is a thing.
My husband’s theory is that part of the problem is that others are not setting up their tents correctly. He has set one up in the back yard - in anticipation of more downpour - to test the theory.
If he’s right, I will be happy to sit in a chair and read while he sets up all the tents correctly ;-).