There are traditional cowboys and tough guys on the list, but the former (as in Stagecoach , 1939, and The Searchers , 1956) is limited mostly to John Wayne, and the latter (as in The Maltese Falcon , 1941) to Humphrey Bogart; and you get the sense these films were chosen more out of nostalgia for their stars than for their dramatic power.
It's clear the films were only chosen because of their dramatic power and strength.