I was confused so I looked up on GoogleCan't agree more. While this is certainly stooopid, it's no surprise that adults are behaving this way. The more reason U10s should be playing sand lot soccer, developing foot skills, having fun ,etc. Hey 10 yr old, don't score.
This made my day...ha..
"Can't/couldn't agree more" (not "any more") is an English idiomatic turn of phrase that means "agreeing fully." Think of yourself agreeing 100% already, so it's impossible to agree even more than that -- couldn't agree more.