"Ain't no kill like overkill." -- SilverRey
When there is no diplomatic recourse. When trade restrictions fail. When there are no other alternatives... they send in the humans. A small team, an individual, an army... Humans are sent in to deal with the problem.
Pinpoint accuracy is preferred, but there are other times... regrettable times, when one despot will simply be replaced with another. The revolution comes full circle with another power-hungry iron fist in charge, promoting those who agree with them, and otherwise making certain that all good things flow their way, and all the bad things flow to everyone else.
It was not a problem of people. It was not a problem of power. It was a problem of culture. There was only one way to kill a culture - and it wasn't in the killing of people. It was in creeping in via cool things and changing the culture by sinister osmosis. Humans are experts at this.