Board Thread:Battle Nations Discussion/@comment-72.210.71.19-20141026162035/@comment-11090687-20141026164954

Probably only to avoid a front row full of Apex Colossus with an Apex Stalker and Apex Bullfrog behind them. Maybe also to avoid spamming of Hunters in PvP, because it is the only (mass) producable Air unit.

I'm not sure though.