Why (if anything) is a planet clearing its neighborhood important?

[halfeye]

Hyperbolic much? The definition wasn't made in haste, nor was it done solely to make Pluto not a Planet.

This sounded rushed to me:

I have been told by an astronomer - albeit one who was not present at the conference, being at the time too junior - that "keeping the number of planets manageable" was indeed one of the principal reasons for shrinking rather than expanding the list. ... From what I understand, from an initial list of nine that could no longer be justified on any scientific grounds, they were faced with a choice between reducing that to eight or expanding it to probably somewhere in the region of thirty. There was no particularly compelling scientific reason to choose one over another.

...

What I don't really understand is why so many people still seem to be put out over a decision about technical definitions that happened 16 years ago.

Speaking personally, I am convinced that the decision was a very bad one. It seems to me, that it is in the spirit of scientific enquiry to be skeptical and critical of any and all decisions, especially if they seem to be wrong on the basis of the evidence, which this one seems to be to me.

Nor does the Oort Cloud have anything to do with the orbits of objects in the Kuiper Belt inwards.

I didn't say, or intend to imply, that it did. I have been saying for some time that a Jupiter mass object in a circular or nearly so orbit far out in the Oort would by the current definition, as I understand things, not be a planet, because of side effects of it being too far from the Sun, which I suggest is a hilariously bad mistake.

And literally everything in the Solar System is going to have a barycenter closer to the sun than the object orbiting the sun; that's what orbiting the Sun means.

For most objects, the barycentre is between the centre of the sun and its surface, i.e. the barycentre is inside the sun. Jupiter may be an exception to this. I was very tempted to say that the barycentre would be outside the orbits of Earth or even maybe Pluto, but I don't know that, so it seemed to me it would have been silly to say it. For a star more massive than the Sun the barycentre of their mutual orbits would be nearer the other star than the Sun, but then we clearly wouldn't be talking about anything remotely like the current Solar system.