Most US medals for valor date to WW1. The tendency to issue decorations for breathing in and out appropriately began in WW2 - after all, the "oversexed, overpaid and over here" crowd had to have something to attract the English girls other than their good looks and sophistication - and reached ridiculous extremes during and after the Vietnam War.   Today, it is easily possible for a soldier/sailor/airman/marine to have 3 or 4 rows (3 to a row) of ribbons without ever doing anything other than going where he was supposed to go and doing what he was supposed to do in a reasonably satisfactory manner.

Valor medal are something else. It is against the (US) law to wear or claim to have earned a valor medal (or military rank) to which you are not entitled, and these people can be, are, and should be prosecuted.