> at least in the case of a manual gearbox
Ok, let's say you go stupid simple for the transmission and have a super basic classic four-speed manual.
Right off the bat, you've got clutch wear. In that e-CVT, there are no sliding clutches. Everything is connected all the time. Immediately, we see a wear component that will eventually need replacing. Not might need replacing, will need replacing. It is a consumable part, designed to wear.
You now have cable assemblies which will eventually stretch over the life of the car. Those will eventually need adjustment. Once again, these just don't exist at all with the e-CVT system.
Now you have a shifter and gear selector. This will need to slip in and out of other gears. Often this is not a perfect shift, imparting wear on the transmission components. Once again, you don't have a gear selector in an e-CVT, this wear never happens. This wear can cause premature failure of the transmission. This is largely controlled by the skill of the operator, sure.
Just a few quick examples. But this is then also an incredibly basic manual transmission, you won't find such a thing on pretty much any recent mass market car. These days you'll see complicated automatics with servos and what not to control the gear ratios, massively more gear ratios, rely on fluid channels to push things around inside, rely on computers to operate them effectively, etc.
And as Retric mentioned, there are analoges for most of the hybrid components in a pure-ICE car. You already have a DC motor set to drive the car in the starter motor. You already have an inverter, the alternator. You're not really adding a ton of new things, you're just massively upsizing some of the things you already have and massively simplifying a lot of the other components.