re: And other arguments
Jewitt has a point though:
Right after Ceres was discovered on the very first day of the 19th century (01 01 1801), the three other larger asteroids (Pallas, Juno and Vesta) were discovered in rapid succession (the last of the 4 was discovered in 1804).
When Jewitt and Luu discovered 1992 QB1, very quickly other KBO's were discovered too.
When the first exoplanet was discovered in 1995, many many others were discovered shortly after too.
Meaning, once a discovery is made, there is a trend towards rapid discovery of similar objects using similar successful methods.
Pluto was left alone as a planet-KBO for 60 years..