That's not accurate. The lunch buddy is there to give the candidate some relaxing time off of interviewing, allow them to get a good lunch, and to ask questions "off the record" to a potential colleague. Informally it is the job of the lunch buddy to make a pitch for why the candidate should consider working for the company, and if relocation is on the table, what's neat about the area and why the candidate should consider moving.

The lunch buddy doesn't get the option to enter feedback for a candidate and often doesn't even get invited to the interview debrief. They really are there just for lunch.

Source: have been a lunch buddy several times.