I think it's both. Lists do practically help us navigate the overwhelming number of options we're presented with, but there is also a large social signaling factor to them. Knowing what restaurants are popular or new or exciting is a way for someone to communicate to other people that food is an important part of who they are. But in order for that signal to work, it sometimes helps to have "canonical" definitions of which restaurants are "in" and lists and critics enable that.
What I find really sad about all this, though, is that it sacrifices the value of our own personal narrative and preferences. The idea that there is a "best" restaurant implies that my experience at it is irrelevant since "best" is apparently a customer-independent property.
That in turn implies that my own stories around which meals I loved are not worth telling to others. I think that's a terrible perspective. I'd much rather read an article about the top ten meals someone had — a narrative about them experiencing the food and not about the food itself — because it's ultimately people that matter.