All the big tubes require longer and more x-rated videos from sponsors. Most sponsors are happy to provide those, cause they don't want to miss out on the sales from the tubes.

Ratios probably suck, but the insane amount of traffic makes up for those bad ratios. If you send enough people to sponsors, some will buy eventually. They also make money from selling ad space, promoting cams and dating sites.

For the tubes it comes down to: traffic = income

To increase traffic, they need longer videos that show more and more. It's irreversible.