Believe it or not, an automatic transmission can pull extreme loads better than a stick. Three things create these advantages. One, the torque converter provides a smooth fluid coupling that acts a lot like a shock absorber between the engine and drive train. It is good on the drive train and rear ends. 2nd, The torque converter provides an additional gear ratio of about 2. 5-1 for additional gearing beyond the straight 4 or 5 speed stick. 3rd, Planetary gear units can pull heavier loads than a main-shaft and counter gear stick transmission. Each pinion provides 3-4 teeth times 4 or more pinions, for a total of 12 teeth or more for pulling. Keep in mind that that is also in a perfect circle, so load and torque are distributed equally around. The stick transmission on the other hand, with a main-shaft and counter gear, only provides about 2-4 teeth at the most at any one time to transfer the torque and load from the main-shaft to the counter gear. Also extreme loads tend to cause these to separate, that can split a manual transmission case apart. Think about these things the next time you pull something down the road.
(Comments by a diesel and automatic transmission mechanic for over 30 years. )
Hmmmmmmm... ... .....