not a catch phrase, it is an engineered goal. Heres low enough..Where is the center of gravity and how do we know when it is low enough to solve the problem of a high center of gravity?
I think the term is mostly a catch phrase. And one that very few even know how to meaningfully apply the concept to a build.
To paraphrase another here, LCoG means fitting the largest tire with the most frame height that results in the most evenly divided shock travel. Any more height is arguably getting excessive. Meaning the overall build isn't any bigger than what is needed to get the most out of it.