Pretty much. I will give the big ones credit though (C6/TH400/747) they can handle fairly big power stock and are pretty rugged when built, but they will go poof before the equiv. crashbox even when built.
That said...They are actually preferred in off-road racing because the driveline shock is constant with the constantly spinning tires and jumps. It actually feels like a hammer in the back with the Pro/Trophy trucks (450-750HP depending) as they lose/grab traction and its like that for hundreds of miles. But they are -totally- maxed trannies with all the exotic stuff inside and at the end of a 500 mile race or especially the Baja 1000, there’s nothing inside them salvagable. You can smell them coming. Just fried.
IF they make it. Tranny swaps mid race are common.
Edit 727 Torque-Flite
I've said this before, but one thing that has always impressed my about the "hybrid technology" is not the total hybrid vehicle itself, but rather the fact that they have replaced the transmission with an electric drive motor.
Why wouldn't a performance vehicle benefit from the massive torque and indestructibility of powerful electric motors driving the wheels with the power being delivered by the high-output engine?