Like many outdoor sports, such as hang gliding, backpacking, cross country skiing, windsurfing, and sailing, ww rafting used to be much more popular. There used to be manufacturers like Stansport that made neoprene rafts that regular families could afford. They were about $100, so a regular middle class person could buy one and not have to have a mortgage on it. People went on many rivers in the class II-III range. Many even made wooden frames for them inexpensively. Sometimes they would leak a bit and you'd have to repump them back up, but they worked.
Then people decided they needed to buy really fancy rafts that cost $5000-$10,000. They were much better rafts. They were better for multi-day trips or class IV rivers or even harder! They didn't leak, but they were huge and you needed a big space to put it in. Many people decided they weren't going to buy in at that level and like the other sports, it kind of died out and not as many people go now. Some people will just buy a trip for a day or two on a river on a commercial trip, rather than buy their own raft.
There is also a niche group of people who bought these expensive rafts and that is their main recreation. There are several multi-day trips that these rafts are good for. Some of them go very slowly down some rivers in multi-day trips.
John S
PDX OR