You're right about more gears in auto transmissions helping to keep the engine at its ideal RPM for torque. There are still more mechanical losses in an auto transmissions since the auto transmission's fluid-based torque converter does not transfer engine rotation as efficiently as a manual transmission's friction-based clutch when the latter is fully engaged.
Can confirm what the other commenter was saying, lockup torque converters exist. Most of the complaints you have are about 90s era auto tech which suuuck hard.
Example, 08 bmw I had with a ZF 6 speed auto. Pain to drive taking off cold in the morning as the software would allow it to slip. Functioned as an old school auto. Normally however, kick it from the line, it would hook up. This was a car with 500+ lbft of torque.
A little software mod and it was probably better to drive (with the paddles) than a manual in terms of engagement. Also let you keep both feet on the control peddals to modulate around the track.
Could also drive this thing for 6-7 hours, arrive and not feel tired.
