I think it is more "obviously wrong in face of evidence and refuse to reconsider" than informed experts per se. Doctors being stuck up about handwashing because

I think it is more "obviously wrong in face of evidence and refuse to reconsider" than informed experts per se. Doctors being stuck up about handwashing because they heuristically interpretted "a gentleman's hands are alway clean" as a descriptive instead of a directive was certainly groupthink. It is possible to be wrong and not be engaged in groupthink or right and lacking logical basis.