"Is he high functioning or low functioning?"
Seems like an innocent enough question, right? And a simple enough one to answer, one might think. But there is so much more to it than that.
What does high functioning mean? What is low functioning? What is the criteria to look at? Is it based on intelligence? Is it based on being verbal? Is it based on being potty trained? Is it based off of aggressive tendencies?
What about the child who is verbal and extremely smart--- smarter than all his peers, typically developing or not. But this child is not potty trained by 8-10 years old. Or ever. This child also has meltdowns that lead to physical aggression towards himself and towards his mother and teachers. By some definitions, his intelligence and speech would warrant that 'high functioning' level. By others the aggression and lack of potty training would lead to 'low functioning'
Then we go to the other side... someone who has no speech at all. They use communication devices to express their needs and can write beautifully. They may not have words to speak... but they are intelligent and find their own way. They may or may not need help with self care, but just the lack of speech alone for many would point to 'low functioning'.
See, this is where the problem lies... autism is a spectrum and is based on a variety of factors... someone may have extreme struggles in one area, but excel in another. Sometimes its a matter of any given day. If you struggle with anxiety you know this feeling well yourself! Some days are good... some days are struggles.
When we try to put that label on an autistic child or adult, it says something. It says for those that are 'high functioning' they are 'more normal', we forget about the struggles because hey, 'they're high functioning'. That doesn't mean their struggles actually are less, they are just focused on less. For many, this can make it harder to get the support and understanding they still very much need. When someone is labeled as low functioning, their assets are ignored. They are seen as less than because they cannot speak or use the toilet, forgetting completely all of the amazing assets they DO have.
And so, I say again... we don't like them, and we don't use them. Ultimately, high or low doesn't matter in the slightest. Autism is autism- in all its high points and all its low points it just IS.