I was surprised to see that was true when I checked the weights. The basic models and the lite touring models seem to be reasonable weights. I had been mostly exposed to the GT series.

With the GT series for 4 panniers and a large handlebar bag the total is over 13 pounds empty!

Swap the rear ones for the TT84 tandem panniers (a setup that I have seen a solo rider using) and the empty weight climbs to 15.5 pounds! He was delighted with his setup. I would have stayed home if forced to carry that much (my full panniers now weigh less than his empty ones). The thing is we were both quite happy with our setups and would be miserable with the other's setup.