Personally, like the vast majority of us, I think anyone who calls in ahead to a restaurant is totally lame and most likely an NPC, but it does depend on where you are and the current culture around you
Most of the time I am meeting friends to hang-out and we will spontaneously find somewhere to eat. I really enjoy that.
Occasionally I am hanging out with friends from out-of-town, or friends with kids who don't get out as often. Then it's convenient to have somewhere booked so we don't end up having to eat at a not-so-great place and 'spoil' their visit, or their one evening seeing friends that month.
Sometimes I want to hang out with a big group. Try finding a place which can spontaneously accommodate twelve people.
Some people have the time and money to plan ahead, some don’t. It’s really all very random
Calling somebody an NPC is dehumanizing. You don't have to agree eith their values, but please don't disrespect their autonomy.