It did though, it's just not in common usage anymore. Per wiki:
But no one ever says it, primarily because it's a stupid name. Guards are called guards because it's their job to guard the QB. There's no one to guard on defense. (I'll ask you to stop there and not continue the logic to why OTs are called tackles because I don't have a good answer.)
OG isn't a thing. It's G. It shouldn't annoy me but it does. See also "centre-half" in soccer, a position that no longer really exists but we still use it to refer to a central defender (who is correctly called a centre back).
No one said when this thread was started that these annoyances have to be significant, or even correct.