There are many reasons anti-amyloid mABs might not work that well besides "amyloid hypothesis is bunk." You are giving them to very late-stage patients, they don't actually work that well if you look at the data, and some people also think that if you disaggregate fibers without a molecule that also inhibits new aggregation, you are just creating more "seeds" that can grow into more amyloids. I think the fact that they do SOMETHING despite all these unanswered questions and also their terrible side effects actually suggests we might be on the right track.