When I was a little kid, there were a hell of a lot of casual snapshooters carrying around Kodak Brownies and Polaroids. Into the late 60s and the 70s, there were a hell of a lot of casual snapshooters using Instamatics and the new even easier Polaroids.
A hell of a lot of people. Picture quality, compared to a smartphone today, sucked. But a hell of a lot of ordinary people carried their Pocket Instamatics around with them and made a religious thing of dropping off the cassette at the five-and-dime store every other week.
As I said before, there was a bubble of interest in higher-quality cameras that began in the latter 80s as cameras with interchangeable lenses and adjustable controls got much, much, much easier to operate with cheap zoom lenses, automatic focus, and computer-automated exposure--all bursting forth in the 80s. That bubble merged with digital imaging in the latter 90s and with the personal computer boom. All those factors of ease and automation in the last two decades of the 20th century served to pull the Instamatic/Polaroid market segment away from the kind of camera that really best suited them.
But this never meant that the people of that market segment enjoyed carrying around the weight and bulk of those cameras. This market segment is of people who like to use cameras to document what they do, but making photographs is not actually per se "what they do." That market segment never liked carrying around bulky cameras.
Cell phone cameras absolutely fill the bill for their documentation needs. It's a perfect tool for their desires. Cell phone cameras burst the bubble created by easy-to-use bulkier cameras.