Yeah I asked a guy at Menards also and he said they didn't have it. So I asked him where their Drop ceiling stuff was located. He pointed me to a back dark row and there it was lol. I took it back to him and showed him what I was talking about. He didn't care, but I felt vindicated :P

The benefit of the weight is it allows you to spend more of the "weight capacity" of your tank or hardscape and not a lot on the False Bottom. The weight is one of the reasons why i prefer the egg crate method over using Leca (clay balls) for a drainage layer.