I dont care about this policy one way or the other, but following is not true: "If the team still wants to do lunch together everyday at an outside restaurant, it would not be easy, especially the logistics, which would be a nightmare"
It is not nightmare, it is pretty easy thing to do and friends groups in work do it almost daily without any problem.
I think they meant taking out the entire company, say 30+ people, rather than just having lunch among your friend group, which is probably very overlapping with your team, and therefore encourages "silos", which the company already has enough of.
It is not nightmare, it is pretty easy thing to do and friends groups in work do it almost daily without any problem.