The 223 is a cartridge that is immensely popular, and the first reason for that is the AR chambering of a like cartridge. (I forget what you call it.)
There were, and are, other 22 cenerfires, that were around when the 223 was designed. The 223 may have some advantages over some of them???, and the fact that faster twists, and heavier bullets are available, may be desirable.
Isn't the 223 or ANY 22 centerfire too underpowered for the Greatland? It IS chambered in rifles, but is it really a RIFLE cartridge. (One that will do a bear, in an emergency.) I know that some guy kilt a bar with one. It was inevitable, with the proliferation of ARs.
If folks gott'em they'll be packin them around..
Smitty of the North