Pluto is a lot closer to Earth's Size than Earth is to Jupiter yet some egotistical Earthlings feel the size difference between Earth and Pluto somehow indicates a different status. It's a totally emotional non rational attitude. Planets are built from smaller pieces. There will naturally be a continuum.

Drawing a line at any size is completely arbitrary. The only thing that makes sense is some non arbitrary criteria like spherical shape. Or, something else where there seem to be clear boundaries based on physical limits like the star masses leading to black holes or neuton stars.

The argument "but there would be so many" is equally stupid. What other classification system is based on how many objects would fit it?