What could possibly be the use for any sort of logic in such cable be, given that on both ends of it there’s already a computer as well?

Maybe because MacBooks can be charged via both USB-C and MagSafe connector it forms part of the safety mechanism against frying your motherboard and/or against arcing during connection/disconnection. Especially on the higher-end of the spectrum (e.g. 16-inch MacBooks with 140W MagSafe).

Sort of like the same way electric car chargers handshake before throwing amps down the cable.