What concentration camps reveal is that modern people are squeamish about killing. Consider the Mongol empire. While the Mongol empire had some things in common with a modern state, squeamishness about killing was not one of them. There are cases where they decided a city needed to be destroyed and they took great pains to make sure that destruction was total. Every man, woman, and child they could find was put to th…
Further, anybody who really understands exactly what the United States did to Japan during WW2 would be very, very hard pressed to declare "modern people are squeemish about killing."
(Seriously, this is almost exactly backwards. Nothing the Mongols ever did could even approach the destruction of modern conflicts.)
> Concentration camps are only necessary now because most people won't stand for such atrocities, and states therefore feel compelled to carry them out in relative secrecy.
Again, this is backwards. Concentration camps are the most basic kind of state terrorism. The goal of modern camps is always to inspire fear in a population in an economically efficient manner. The same is true of historical genocides and slavery. They were tools of terror. What previous governments lacked but the modern state possesses in abundance is the ability to track, contain, and feed large populations. Once you can do this it makes much more economic sense to terrorise your enemy's population than it does to completely annihilate the city (and destroy lots of valuable infrastructure [1]) or enslave the population (slaves are often not very productive from an economic perspective). Hence concentration camps.
The article is probably a bit off too. There are even more sophisticated forms of state terrorism available today which largely obsolete concentration camps. Mass surveillance (once you can convince the population they are always being watched most will self-regulate), mass debt (if you really want to control a man give him a 30 year mortgage, to control a country give them insfrastructure loans) and mass institutionalization (force most people into prison or universities). You are far more likely to see modern statesmen advocating for more surveillance powers and "tougher" laws or economic fines/seizures against whoever happens to be enemy.
[1] To get down to it, the two basic reasons modern states don't annihilate population centers is (a) nuclear weapons which blow out all cost/benefits calculations (b) global trade has produced highly interconnected goods and services networks. Note that (a) and (b) reinforce one another.