That is utterly nonsensical. Are there HUGE tracts of land where 100 ton railcars or concrete blocks grow on trees?

If not, then how are you getting them there? On a per-mass basis what do you think is easier to transport, railcars or water?

Transporting adequate amounts of gravity storage medium is not at all a competitive advantage for non-hydro gravity storage. For that matter, it does not even constitute a meaningful factor except as a disqualifying one for the nonsensical ideas people somehow seem to get funded.