The one thing that bugged me the most at my sons IEPs were the experts that liked to spout information about autism. He needs this as children with autism are low toned. Its important that you have a lot of knowledge when working with autism. We need experts.
However, it does not help that much in making decisions. In deciding what is best for the child in question. Because every child is different, you need to know the child.
Teachers are taught to respect and include parents in planning meetings. I think they still often fall short. However, they are important because they know the child the best.
Professionals, I think, do not look to the parents because they often do not have the cache of information on autism that they do. That info is great for guidance, but for every generalization made (yes by me included, there are just as many exceptions).

I know this because at my son’s IEP, I saw how the professionals talked. They did not know that I had that same information. I did not confront them, but I did not need to. They were able to get my child’s educational needs met.