You might well be right, but do you have actual numbers to back that up?
I don't think total usage numbers have ever been publicly known.
But I was indirectly involved in the photo-finishing industry during my younger years - my father was the Customer Service manager at the Western Canada Kodak lab and was the person responsible there for interactions with a large number of Kodak dealers throughout western Canada who sent customer film to that lab.
The amount of customer film - movies and slides mainly - that went through that lab between 1961 and 1983 was absolutely huge. But that amount was eventually dwarfed by the amount of print film that went to mini-labs instead.
When I started working in retail camera stores, 35mm was popular, but the people who used snapshot cameras had no end of trouble with loading and rewinding film. The 126 format was incredibly popular, and 110 thereafter was in many ways more popular. Almost none of those people were willing to struggle with larger roll film cameras.
Larger film sizes are wonderful - particularly with modern films. But the mass market has never been focused mostly on image quality. It has been focused on flexibility, ease of use, speed of results and economy.
Even in the days when volumes were huge, customers were incredibly price sensitive. One of the camera counters I worked at was at a large department store. From time to time we would have sales on our photofinishing services, which were already very competitively priced (and frankly of middling quality). People would save up their films and only put them in for development when we had a sale on.
At the same time that was happening, the really high quality lab I was using was doing great work with the 120 Vericolour I was sending them, and giving me fast, pro quality results at excellent prices.
The volumes that supported most of the industry were in those 126, 110 and 135 films that snap shot amateurs were using and we were sending off for them (overnight service) for middling quality photo-finishing.
The really good quality stuff had good volumes too, but they were small in comparison.
FWIW, I've got my Dad's 110 Kodachromes and, when projected using the 110 projector, are quite nice.