I updated the functioning labels section of “I’m Autistic. Here’s what I’d like you to know.” with selections from “Uniquely Human: A Different Way of Seeing Autism”.

When mothers and fathers hear the term low-functioning applied to their children, they are hearing a limited, piecemeal view of their child’s abilities and potential, ignoring the whole child. Even when a child is described as “high-functioning,” parents often point out that he continues to experience major challenges that educators and others too often minimize or ignore.
When professionals apply these sorts of labels early in a child’s development, it can have the effect of unfairly predetermining a child’s potential: if “low,” don’t expect much; if “high,” she’ll do fine and doesn’t need support.

Source: Uniquely Human | Dr. Barry M. Prizant