Originally Posted by
shinta|hikari
Finally got to watching the episode and wanted to comment on this statement.
This is exactly what happened. He damaged his arms too much and making them do any more risks permanent disability, so he is now going to use his legs (with more care to avoid damaging them like his arms). As for him being a crippled version of All Might, I tend to disagree. He can still use his arms, but he wants to avoid doing so because of how damaged they already are.
Also, All Might is a terrible fighter. In all of his fights, he only used his fists to fight, which is a retarded way to do battle (i.e. why MMA is superior to boxing in actual combat). Izuku has always been more flexible and smart (All Might is as dumb as bricks and always has been, as explained by people who know him). Izuku can become an all-rounder, using his punches, kicks, and wiles to defeat the enemy. All Might has always just been about pounding them to death, which severely limited his prowess.
With these things considered, he will probably surpass All Might in overall effectiveness in the future.
Edit: BTW, I searched around for explanations about All Might's muscle form, and it seems even the fanbase is confused about it. The best I could find is it's something separate from One for All and is there for comedic effect and therefore completely unrealistic.
Edit2: To be fair, the reason why I am confident about my interpretation is because I can understand Japanese. After Izuku kicked the rock, he said, "If I'm worried about my arms, I should use my kicks as my main (weapon)." He never intended to stop using his arms but to simply use kicks more because his arms aren't in perfect condition. The horriblesub translation omitted the main part, implying he'd just stop using his arms.