Sure, at that moment in time. You are, however, discounting the abilities of clever people to innovate and improve the $/kg performance. I prefer to think we engineers are pretty good at reducing the effective cost of tech over time.
However, none of this is about Saturn V vs Shuttle vs some other platform. If NASA remained the sole customer over that period, there would not have been adequate incentives to drive that cost down. In that situation I think improvement would have been slow independent of platform choices.
It is the telecommunications age creating scaled incentives that has led to cost efficiencies and companies like SpaceX (and many others) competing to drive those costs down. Lacking the current scale of global incentives, SpaceX and others still wouldn't exist. They certainly couldn't have acquired the necessary funding back in the 70s.