I think in fact there is always a synergy effect to centralization and an efficiency effect to decentralization. The synergy is quite obvious and explains why

I think in fact there is always a synergy effect to centralization and an efficiency effect to decentralization. The synergy is quite obvious and explains why big companies and nations are able to survive in spite of the lack of efficiency. The efficiency probably stems from a smaller (communication) distance between organization members. The efficiency effect is IMO less well-known hence the comment but you're totally right. From that perspective the above-mentioned tactic amounts to a removal of synergy. If you look at it locally (and this point doesn't really apply to armies and companies but to, e.g., herds of animals), you also cut off the communication to the other herd members so it's a win-win from the predator side.