Yes, it does seem like that at times. It can leave you wondering if you're just missing something obvious. However, getting it in print does help me think it through. Once I started thinking about how current flows from wheels to decoder to motor, the problem became clear.
It is expensive, but I only had the one to do. You're also getting the internal lighting.
EBay has had some decent deals on that decoder, but not often. I did a Best Offer for about 2/3 of the asking price. (I had the earlier version and sold that one. That helped finance the new one.)
Ben