... a ref to a single scalar ...

My guess about a possible rationale for this is that the strings being handled are in reality very long and DAN0207 wants to avoid making a bunch of copies of these long strings (e.g., to pass to subroutines). In a case like this, I'd agree that taking a reference to a scalar (string) and passing it around could be quite advantageous in the right circumstances. But this is all just guesswork.