I apologise then. I was told by a friend, who was told by a friend etc. who knows how it was first found out, perhaps the alpha testers were made aware of it by devs.
In any case it's very useful for making your shock infantry "blob" together so that they attack the same point. Or, because units in square formation are very passive for some reason, I make them into a square myself but they still retain the aggresiveness of line formation which helps in killing cavalry.