[SmokingJoe]

It worked for the Soviet Union in “winning over” its own people. It worked for the British in South Africa, and for the Spanish in Cuba,

For how long?
The Soviet Union is no more. The British got defeated in South Africa by the Boers and Castro ended Batista’s rule in Cuba.
America was in Afghanistan for over 20 years and still got kicked out by a bunch of Taliban savages. No amount of US genocide would have beaten the Taliban. They are worse savages than we are and pretty good at genocide if it comes to that.

[buwaya]

The British won in South Africa. The reconcentration policy was used to put down the guerilla war (stage 2 of the Boer War). South Africa was a loyal colony in WW1 and WW2 and remained part of the Imperial economic system into the 1970s.

A military strategy like reconcentration is meant to solve an immediate problem, like a guerilla war, in a particular place, not solve all problems of governance and economics forever for an empire.