Music theory...

Hey guys.
There has been a question that has been biting away at me for ages, so I asked my dad on the way to school.
Your wondering what my question was?
It was 'Do singers do all the work?'
My dad said'No'...
Well he explained to me that there are alot of people who are in the business and they all do something for the song. People work on the backing track, the lyrics, the paragraphs etc etc.
So basically I learnt that singers don't actually do muc. They can take all the credit why don't they?
I thought they worked so hard!
*SIGH*