The door-to-door ministry was a business model to sell publications of the Watchtower Bible and Tract Society. That is why members of the cult are referred to as "publishers". What changed?
The fear of losing their tax exempt status cause the WBTS to go to the donation program. This had an immediate economic impact on the WBTS. Members would purchase literature for cash from the WBTS. Then they would sell it to the public for the same price. Many members would then donate that money to the WBTS instead of using it to purchase additional literature. So, that Watchtower Joe Q. Publisher purchased for $0.25 made the WBTS $0.50. It probable cost the WBTS $0.05 to manufacture it.
I know for a fact that most publishers did not make sufficient donations to cover the cost of the literature. I donated $0.00 whenever I picked up magazines and books. This is what lead to the diminishing size and frequency of magazines, softcover books, and eventually download-only literature.
However, because the door-to-door ministry is the trademark of Witness activity they couldn't cease it. So, they switched over to showing videos on self-purchased tablets. In addition, cart Witnessing began.
I am sure that more than once Witnesses saw some inactive members house while out in the ministry and discovered holiday decorations. Of course the dry snitched on the inactive member. Yes, that member was probably disfellowshipped. This is not the purpose of door-to-door witnessing.