Thing is, the fact that you can reduce the nicotine dosage does not necessarily mean that people will; unlike cigarettes, it's trivial to also increase the nicotine dosage many times.
I don't think a significant amount of people do that. Coming from someone with a lot of experience vaping (actually helped me quit smoking), it's somewhat difficult to find ejuices with pleasant flavors (anything that's not a stereotypical cigarette flavor like menthol) above 6mg, and around 9mg or higher, the nicotine flavor becomes quite pronounced and overpowering, and your flavor options are severely limited.