Redefine your criteria for worth then if I misunderstood: Weapon, not so worthless concerning it's an first strike ICBM meant to deliver MIRVs and to completely saturate the target area, much like the LGM-30 Minuteman III. It preforms it's job well, but for the user of that weapon, well they won't get to see the results.
I am perfectly calm
Fact is no one tried this with analog computers.
It is not so much the computing power on the ground that was lacking (house-sized computers in the 60s had all the capacities of a iPhone except graphics) but the fact that you couldn't transmit it fast enough to the missile.
So it is rather advances in computer miniaturization and data link technology.
Iskander is a TBM