I think you’re right in the 70’s there were very few companies but they did everything.
Facials and rimming in the 80s and 90s and even early 2000s was highly unusual and I don’t recall seeing it in Falcon, Catalina and other main stream companies. First time I saw cum eating was on Sean Cody and Corbin Fisher. When Bel Ami started doing it we even talked about it on here.