If you weren't a gamer (or alive) at the time when quakeworld came around, you might not appreciate how amazing it was for multiplayer games on the internet. On dial-up, you were lucky to have 150ms latency. Before client-side-prediction, that latency applied to every action you took in game, including player movements. Hit the up-arrow, and you wait 150-300ms before the game responds and moves your character forward. CSP really was an amazing break through, and made multiplayer action games feasible on the internet.
This is particularly relevant now, that we are entering the era of cloud-based streaming game platforms, like Stadia. The latency problems of the pre-CSP 90's will be rearing their heads again. Its going to be interesting to see how these same problems will be tackled in this new context. Internet speeds are higher now, but so are our expectations.
I doubt we'll have the nice, simple dotplan files that Carkmack left for us to read and remember, from all the SRE's at Google, sadly.