Of course it didn´t, and at least I have never implied so either. It turning him into some bionic person that is.
Without the steroids he would in no way, shape or form be a professional footballer today though. Therefore, without the steroids in his early teens - there would be no "Messi the footballer" as we know him today. Nothing controversial in that at all, and I think even Messi would agree. In that sense it is difficult to say that he isn´t now reaping the rewards of the steroids he took/was treated with then.
I am genuinely surprised why this topic has never, to my knowledge, been raised in Messi´s case. The question was raised in regards to Lance Armstrong, and it takes some nerve to go after a guy treated for testicular cancer! There are quite a few cross country skiers as well on banned, performance enhancing prescription medications, and there has been a decent amount of debate on that.