When I was younger they were used for a small bag full of my packed lunch, and on my back would be backpack full of grooming kit and off to a show we would go
Some other people hacking past commented that my whip was rather long, couldn't figure out if they were joking or not! I didn't know if they'd clocked the clipped on lunge line and the roller and chambon across the front of my saddle!
When my friends and I used to go on day rides involving a pub lunch (happy days!), the horses used to wear their headcollars under their bridles, and we used to clip their leadropes to the D rings, then we would take saddles and bridles off when we reached said pub, and tie the horses up outside. It was a very equestrian-friendly pub and had safe tying-up facilities. So there is your true alcoholic's reason!