True, but that's a waste when some of the best rails don't require it, IMHO.
It's only a waste if you're happy with the 2 piece design and are willing to limit yourself to 2 piece systems; thereby excluding some of the best FF rail options available such as KAC, Larue, and DD's other designs. The 2 piece rails hold no advantage over single piece FF rails except for a user friendly installation.