Umm, not to be contrary, but "old fashioned" automatics have clutches and pressure plates also running in the fluid. Lock up on torque convertors are the same deal: friction disc running on a pressure plate in the torque convertor and running in trans fluid. Smaller diameter than a manual, but there's multiple clutches, so same (if not more) friction material to beat up the fluid. They deal with slippage and heat just like any other "wet clutch" system.
It's also easy to make a manual shift automatic though both mechanical and electronic means. manual valve body or if the trns is electronic; it's a simple coding change. My 2016 f-150 is a 6 peed auto that I can shift like a standard any time I want with the flick of a switch. They typically run out to the 100K mark before OEMs recommend fluid/filter change. And in my truck, good luck punishing the fluid harder in a C8 than my auto does when I'm pulling a 9,000-10,000 lb trailer.
A manual shift automatic is not exactly "new" technology....even if GM is touting it as so and using a little different scheme from what's been used so far.
Biggest difference I see in their ad hype is the speed at which it will "manual shift". Of course, that it's rear mounted and a "transaxle" is also different from what could be considered an "old fashioned" automatic.
I'm going to wager the heat management scheme isn't shedding the heat as quickly as they had hoped. That's a reasonable assumption given the fact the entire drivetrain is buried in the rear of the body. if you want to drastically shorten the life of automatic trans fluid; overheat it or run it hard and hot for a prolonged time.
With "rear everything" in a C8, all the cooling has to be done by trying to route air in to the bay or getting the fluid out of the bay to a cooler of some sort. Getting the fluid out to a cooler is actually a great cooling scheme as anytime you can get it out of the component for a longer time will bean more temp delta. It also means the system can hold more fluid, which also helps with cooling. Combine the rear mounting with the usual "fuel saving" fluids (IE: thin) they use these days, and it likely ads up to a decreased life expectancy for the fluid.
Of course, that's all just speculation on my part. But it's based on roughly 40 years of automotive/engineering experienceand understanding how this stuff work on the "micro" level. That's 40 years of working on them, not just owning/driving/admiring them.......
