spacepirate You're right that the insights aren't as accurate as a scientific experiment in a controlled setting with a sample size of thousands. However, we can pretty reliably identify trends.
Imagine a performer with 20 videos from 5 different studios. Now imagine that in 18 of those 20 videos, the videos are among the best compared to other videos by the same studio, released around the same time. You can use either likes or total minutes watched as your metric.
While I wouldn't say it's scientific fact, I'd be pretty confident to suggest that she's a popular performer. Of course, there is a very slight chance that each of those 18 videos were an outlier. Perhaps, there just happened to be a better director who filled in that day and didn't shoot for the studio again. Perhaps they featured camera angles that they don't normally feature. Maybe the setting/storyline was much better than the studios' usual ones. While you can't rule it out, I would argue that it's unlikely to happen 18 different times out of 20.
If we extend this to genres and settings, we can be even more confident. There are probably thousands of teens vs milf videos that we can compare. For the same studio, same director, same camera angles, how well do teens perform when compared to milfs? What about if a scene features a nurse costume?