People and fans feed off eachother. All it needs is a small section to be continuously supportive and loud, and others will naturally follow. This is why a singing section would be huge.
It is almost guaranteed that it will help the team, and helps drown out the odd moan and groan from the crowd. I mean, if the players of one of the best teams in the league are making a lot of errors with that atmosphere, imagine what it would do to Burnley?