That article is quite misleading. That is not the case these days. There are some cases where POT is required (compressing using PVRTC for iOS and ETC1 on Android[1]), our renderer does not require all textures to be POT.
[1] ETC1 is forced to be POT only because Android devices that use PowerVR GPUs require ETC1 to be POT. Other GPUs do not require ETC1 textures to be POT, but we have to support PowerVR chipsets as well.