Why Pluto is so amazingly not a planet (feat my man Mercury)

Pluto orbits the sun with a highly irregular, elliptical orbit at over 100 times the distance Mercury does. Pluto occupies a region of the solar system inhabited by potentially hundreds of other similar-sized, similarly-composed objects, whereas Mercury's nearby objects are three non-disputed terrestrial planets. Mercury is 30 times the mass of Pluto and over twice its size.
Pluto was discovered 85 years ago before we knew of any other trans-neptunian objects, its size was vastly overestimated and it was hurriedly included in the list of planets. It was later grouped in to a different group with other objects that had more in common with it once they were discovered, much like Ceres was 140 years earlier (you don't see anyone complaining that Ceres isn't a planet anymore).
Mercury shares the most in common with the terrestrial planets and is thus classified with them. As for the large moons of Jupiter, Ganymede is the largest satellite in the solar system, and only very slightly larger than Mercury, and far less massive. And really, the size of moons shouldn't have any impact on the way we classify planets and dwarf planets.
Sorry if I've come off as brash or insulting, I don't mean to be, I'm just adamantly against Pluto defenders. This post isn't aimed directly at you, but those who think that Pluto should be called a planet just because they were told it was one years ago in general. I was taught a 9-planet solar system. In 2006 Pluto was reclassified in to a much more sensible group. And, unless it fixes its orbit up and grows about 10000 times its size and mass overnight, that's the end of the story.