only type of 'sick' party we all participated in, all of the kids in our extended family (cousins and us) would stay at one place when someone came down w/ it. Basically all over and done w/ at one time, and easier on all. I haven't heard the likes of these parties for a while, so more than likely, docs may frown on it, or the vaccines have arrived full force, thus no need.
One thing I do seem to remember, was that adults getting Chickenpox was not a good thing, they seemed to be impacted more adversely w/ the C. Pox, so not a good thing.
Origins and Purpose
Chickenpox parties became popular in the United States during the 1970s and 1980s. The idea was to deliberately expose children to the chickenpox virus at a young age, under the belief that contracting the disease early would lead to milder symptoms and lifelong immunity. Parents would organize playdates where healthy children would interact with an infected child, often sharing items like lollipops to facilitate the spread of the virus.
Wikipedia