I agree with the semantics, but restrict usage to the very narrow case where the variable has no other use than to convey a value from a visible outer scope to

I agree with the semantics, but restrict usage to the very narrow case where the variable has no other use than to convey a value from a visible outer scope to a visible inner scope, where both together are less than a few lines. In that case I prefer the single character over a longer name precisely because it is clearer. Note that x,y,z don’t really qualify as abbreviations since they are the full name of the component, so they can be used when the outer scope is not visible — eg as a parameter.