Towing with boards in racks

While sitting out the midday heat with some frosty one, we noticed there were a lot of boats showing up with their boards already in the racks. I have never pulled my boat with boards in the rack and don't really think that's a good idea. My buddy had his in the back of his truck last year and it caught air and flew out and went through another cars windshield. Luckily no one was in it but if there had been they probably would of been killed.

Just was curious about other boarders opinions on this.