I agree as well. The Automatic Transmission is simply an alternative method of shifting the Manual gears. It's really misleading because the transmission is not the 'Automatic' part of what is going on. It is the Clutch Engagement and gear changing action that have been automated, (no clutch lever and no shift lever). The transmission gear clusters are identical.
However, it is the transmission gears, not the engine, which wear the oil out. That is why, in most applications, the engine has a specifically formulated oil and the transmission has a completely different oil designed especially for that particular environment.
But, to save weight and size, these 2 very dissimilar mechanisms are combined in most light weight machines, including motorcycle applications. This puts a real burden on 1 oil to do both jobs well. That is why I encourage people to consider using a better oil.