Why is 劝ing so common -or- popular in Chinese?
At first it did mean exhorting or admonishing in classic Chinese, but gradually the meaning broadened. Now any advice of suggestion could be called 劝.


Your parents are having a fight? You 劝 them to stop.
A stranger smoking in public? You 劝 him to give up.
Your student can't form a proper sentence? You 劝 him to learn some grammar.


This is a process the linguists call semantic shift. Dog used to be a specific canine species, but gradually it becomes canine in general. Bird used to mean "young bird" then it becomes avian of all age. 

Humans are fallible, whether as individuals or as a species.