Hmmm, You may be right about that.
All I know for sure is what has worked for me. I have not ran a ground specifically from the alternator to the frame, but I do have a #8 wire ground from the engine to the frame to assure a good ground for the charging system and electronics on the EFI engine...
I am not an engineer, but my experience with Mustangs and locating the battery in the rear with a ground strap to the frame has led to issues with the ECU grounding properly and in some case burning them up.
What does work is to use a braided ground strap of adequate size for the amp load and...