This is true as far as tonsils.
According to The rise and decline of tonsillectomy in twentieth-century America Journal of the History of Medicine and Allied Sciences vol. 62, pages 383-421. which states:
Between 1915 and the 1960s, T&A [tonsillectomy/adenoidectomy] was the most frequently performed surgical procedure in the United States. Its rise was dependent on novel medical concepts, paradigms, and institutions that were in the process of reshaping the structure and practice of medicine. The driving force was the focal theory of infection, which assumed that circumscribed and confined infections could lead to systemic disease in any part of the body. The tonsils in particular were singled out as "portals of infection," and therefore their removal became a legitimate therapy. Nevertheless, what kinds of evidence could prove that tonsils were portals of infection? How could the effectiveness of tonsillectomy be determined? An inherent difficulty was the absence of any consensus on the criteria that would be employed to judge its efficacy. Yet tonsillectomy persisted despite ambiguous supportive evidence. Although criticisms of the procedure were common by the 1930s, its decline did not begin until well after 1945 and involved debates over the nature of evidence, the significance of clinical experience in the validation of a particular therapy, and the role of competing medical specialties
See also the presentation History of Tonsillectomy which explains that in early 20th century the procedure was considered a "general measure to promote good health" and quotes a 1939 reference:
The doctors had coolly descended on the school, taken possession, lined the children up, marched them past,
taken one look down each child’s throat, and then two strong arms seized and held the child while the doctor
used his instruments to reach down into the throat and rip out whatever came nearest to hand, leaving the boy
or girl frightened out of a year’s growth and bleeding savagely