User blog comment:Iconoclassist/Power inconsistencies/@comment-33986849-20180714083648

There is an explanation as to how. When ofa passes down the current user is able to access the strength of the previous users as seen when all might has used it several times. Deku isn't as strong as all might because 1. His body isn't able to handle going all out with it yet, and 2. He's only been using his own strength and not stacking the other users' power on top of his own