Maybe someone has already brought this up, but a news article I ran across:
https://www.cnn.com/2020/12/03/health/churches-covid-1918-lesson-wellness/index.html
brings a question to my mind. What role did the 1918 flu, which had similar isolation as COVID but without the benefit of zoom meetings, have in the decimation of the Bible Student movement in the early Rutherford years? There was a lot going on anyway, with the death of Russell, WW1, Rutherford in jail for a year, etc, but the isolation of the members must have had a role in distancing the people. The breaking or loosening of personal bonds and friendships makes it easier to leave, whether a church, a job, or other association.
Just a thought