I think Joel's article glosses over a point that most of the con arguments here don't notice: in order for this to work, you have to set up a group of coworkers who mesh spectacularly well.
Fog Creek has pretty obviously done that; it's one of their top priorities. I've worked at companies where lunch is communal and companies where it isn't, and it seems to me that the difference has less to do with personality types and more to do with cohesion.
Put differently, the types of teams who want to eat lunch together are the types of teams you should want to be on. The company shouldn't need to enforce it; they should just help to facilitate it.
This is unfair. Extroverts are energised by social interaction, but introverts are drained by it, so they're going to find mandatory group lunches tiring and unpleasant in the long term regardless of the cohesion of the group.
So perhaps that's what "cohesion" really means in this context: hire a bunch of extroverts. Bully for Joel.
There are introverted people who are largely introverted because they find the dance of formal social interaction puzzling or unrewarding. Once that's taken care of for them, they're perfectly happy interacting with others and crave being social.
Then there are sorts who are fine with social interaction but rebel against perceived social obligation or pressure to enjoy or do something. They become angry at this pressure and instead choose to alienate themselves.
I don't think I'm necessarily in the last group. However, I bristle at the idea of not being able to have my own personal time to daydream without interruption while I cram food into my fat idiot face.
Fog Creek has pretty obviously done that; it's one of their top priorities. I've worked at companies where lunch is communal and companies where it isn't, and it seems to me that the difference has less to do with personality types and more to do with cohesion.
Put differently, the types of teams who want to eat lunch together are the types of teams you should want to be on. The company shouldn't need to enforce it; they should just help to facilitate it.