PS4 didn't have system sellers in 2015 on the level of Pokemon + Smash. Yet alone a system seller breaking software records like Smash. We have historical precedent of a console (X360) outselling another console (PS3) entire year with just November + December sales. It's not impossible.
PS4 also isn't a hybrid, drawing sales from two demographics, and has direct competition in the home console space with the XOne and to an extent PC's. On top of all of that, it had the higher price (even with temporary discounts). However, this can also be accredited to Nintendo for taking a risk and succeeding.
Nintendo predicted 20 FY. Many Nintendo fans on this site expected 2 Million+ NPD for December.
Obviously great Switch numbers. It just isn't outselling the PS4 launch aligned. Which speaks to what a beast the PS4 is!
The ps4 had system sellers in almost every single month in 2015. I consider 2015 to be the first truly great year for the ps4 in terms of software.
The switch is currently ahead of the ps4 launch aligned. Worldwide there is a gap of over 3 million in favour of the switch currently. This will of course shrink once ps4 hits it's holiday while the switch goes into the quietest time of the year. But still the switch is at the very least performing on par with the ps4 launch aligned.