Comment by adolph

It seems as though Pluto's primary problem is "clearing the neighbourhood." Given Pluto's orbit travels closer and further from the sun than Neptune, does Neptune also have the neighborhood clearing problem since it has not cleared Pluto?

  In celestial mechanics, "clearing the neighbourhood" (or dynamical dominance) 
  around a celestial body's orbit describes the body becoming gravitationally 
  dominant such that there are no other bodies of comparable size other than 
  its natural satellites or those otherwise under its gravitational influence.[0]
  

https://en.wikipedia.org/wiki/Clearing_the_neighbourhood