I think teams run up the score too often and yes backups should play

I think teams run up the score too often and yes backups should play.

This prepares them so when they do need to play for injury, they are ready.

However, every once in a while, in the Chargers case, frequently, teams blow big leads so that is an issue, but the risk of injury when leading by 3 touchdowns to me isn't worth it. You should be able to play your backup a series.