Cross party communication is very important. There's a lot of bad blood that gets associated with the person and to the linkshell this person is equipped with at the time.

To me, the priority of a camp goes to:
Appropriate level ~ A party that is in the appropriate level range to chain off these enemies.

First come, first serve ~ A party that has been dwelling at the camp before others.

Farmer need before greed ~ No one is at the camp, farmer needs some components to complete an item or series of items.

Farmer greed and power leveling one person ~ Are at the bottom of the priority totem. They should be the most flexible when it comes to the above. If a farmer is going for a stack of 99 to cushion an XP grind, make multiple replacement sets (to cover materia'd items), or looking to sell the components, then this is greed (not a bad thing). But would hope they would be more flexible to even a new party coming up to the spot, since the farmer could be at the camp for an indefinite amount of time. Or the power leveler that is only power leveling one or two people. Be flexible. If you see a party of six trying to grind on the same monsters and they want to be power leveled too, and you have room? Don't resist, be flexible. You were power leveling anyway. And if you were adamant about no one joining you, you and by association, the power level-ee, have set a bad impression to a party of six or more players, who usually end up discussing their disgruntlement in party and in linkshell. And bad blood continues.

The exception to most of this? A level appropriate party of eight that gets power leveled and hands the desired components to the power leveler as compensation.

I've revisited my post after being distracted for a while, it's probably incoherent.