I think I have an example of how cool function can be
I am working on a Campagnolo Euclid bike right now. A previous owner was probably not very happy with the original shifting, so had the shifters and rear mech replaced with SRT600 and STX SE. That is a bit too blue collar for this aristocrat, so I decided to swap to XTII thumbies and mech. The cassette is an 80s Maillard screw on example. Of course no HyperGlide. No, big burly teeth instead. Heavy Sachs chain. I had some cables laying around in a colour I like, but they were brake cables, no gear. I anticipated I would have to go with friction setting on the thumbies. Fine with me. Anyway, I attached the cable, gave it a try in index mode and what happens: flawless performance. I say cool.