This was a dreadful experience, and I know those of us who depend upon someone to push our wheelchairs always worry that when we have connecting flights something will happen and there will be no wheelchair.
I do think you exempt AA inappropriately. I think the carrier is obligated to help you reach your connecting gate or the exit of the airport. We fly Delta almost exclusively. Several years ago I had a person in Atlanta who did not want to push my wheelchair. He left me in a restaurant. I called Delta. In five minutes there were five people around me. Three were from Delta, and one of the Delta employees was in charge of disabled care. Of course I immediately received exceptional service, and have had no other problems. I do, however, carry this lady's cell phone number wherever I go.
If what happened with you with AA happened to me with Delta I would receive an apology letter with a $100 voucher even if I did not complain about the lack of wheelchair service. I think you should complain to AA.