For the record my character doesn't have amnesia, and I did write up a detailed origin.
Don't worry about what another player has written to describe his character's background. It's their game and it's their character. To be honest it's refreshing to see that someone even bothered to write a background at all.
There are lots of people who play this game to role play, but others do not. Sorry but you can't make them. People are going to do what they are going to do. I am a roleplayer, but I don't expect everyone to role play along with me. If they do, swell if they don't thats fine too.