Pluto's downgrade was simply because we found potentially thousands of more Pluto's.

The argument I've seen skips the step that the new definition was created to include those other Pluto like objects.

They jump right to how the planet definition was updated to not have overlap or ambiguity with Pluto and therefore was about creating a way to exclude Pluto rather than creating a definition that doesn't lead to declaring there are now 50 planets.