You can think about it this way -- approval voting allows you to vote strategically for a candidate (in case you are worried about the lesser of two evils winni

You can think about it this way -- approval voting allows you to vote strategically for a candidate (in case you are worried about the lesser of two evils winning), and then allows you to also vote for anyone you actually prefer, guaranteeing this can't hurt the strategically chosen candidate. This would allow third parties to see real support, and then go on to win subsequent elections.