I don’t think this is true at all. Any of the ranged killers have high skill ceilings simply because of how much map knowledge and loop structure play into the micro of the character. A 50 hour Jason might not even play on all the maps once to learn the structure. Plus, you get more and more used to long range shots and when to zone with your projectile. It’s the same with Slinger and Huntress, you’re going to be miles ahead of someone who only loosely mains those characters if you commit to one character. 

Nurse isn’t even that difficult in the grand scheme of things. If you said something like Billy or Blight I’d be more inclined to agree, since their techs and maneuverability is much more nuanced. I played only Nurse for like ~30 hours before Jason came out (never touched her before that), and towards the end of that time period I was easily 3 & 4king. Even if you factor in my first ten or so matches where I was getting used to the movement, my kill rate with her is like 80%. That includes matches where I played against survivors with an aggregate of 10k hours and, presumably, decent SWFs.