What does that have to do with PS4 still selling gangbusters and switch barely being up year over year?
Because that trend can translate in less people adapting to consolegaming from an early age,an age that those people normally get a nintendo console and when being older they just immidiately jump to the more mature console being the PS4 so that could explain PS4's gangbuster sales in comparison.
Just speculation ofcourse. :p
Edit: Although the switch sales look fine to me,also worth noting they come from the lesser userbase that was the WII U.