From what I read your statement is accurate. From speaking to people who are going through the new infusions Leqembi and Kisunla get rid of amyloid plaque doesn't mean the decline stops, and if the disease was driven by it then it would stop.

Also, studies show some slowing using these new drugs, but the disease still progresses. Therefore, the plaque is most likely a symptom. It could be the driver in some of the cases though, I think in genetic PSEN1 alzheimer's. I've read a paper discussing issue with the body not removing it and allowing to build up.