In many scientific research projects the same dangerous theme keeps surfacing: monolithic thinking, with “no alternatives allowed”. I feel this is very detrimental to both scientific progress as well as to the broader society.
In any case the whole amyloid system is involved somehow, I think that much is very likely. Just not in the way that the visible amyloid fibers are the cause, but might just be another symptom. This is not anything like heretical talk, this suspicion was pretty much mainstream when I studied biochemistry ~15 years ago. It was only a hypothesis, but it certainly wasn't suppressed.
That might be part of it. I think a bigger part is, "we don't know what X is so we can't measure it, but Y seems to coincide with X and we can measure Y, so let's focus on Y".
This probably happens a lot and sometimes it works out, but it also often doesn't. It failed with dietary cholesterol, and Alzheimer's is the just the latest big failure of this approach.
But "monolithic thinking" is also accepting established theory. Unlimited diversity can open the door to all sorts of crap - I don't want "diversity" in whether a doctor accepts the germ theory of (some) disease, the existence of viruses, etc.