That is true. Rep ranges 6 and under draw little on glycogen.
The idea behind the thing I read was that one shouldn't drop the rep range in the MIDST of cutting. So, if you've been doing 6-8 reps, you shouldn't go lower during the cut.
Again, though, that doesn't really make sense, because it is essentially saying you shouldn't seek to progress.
I wish I knew where I read that and who wrote it, so I could read it again.