If I want to go meet a friend for a drink or food, I have to lug around a backpack, keep an eye on it to make sure it's not stolen. If I wanted to have a beer or wine, I can't because I may need to work at any point.
Favourite band is performing? I suppose you could take a backpack and the laptop to the venue, but again there's a chance it's pinched, and they'll make you check it at the cloakroom for the performance.