From Romans, by Philip C. Gehlahar

Often the weak are perceived as strong. They may speak louder and longer. They try to control other people because they cannot allow them to be different. They judge other people because they cannot tolerate those they cannot control. Paul does not address the message to the weak in faith. They probably would not receive it, because they are weak and could not handle criticism. Niether are they able to change their weakness and start being strong.