Just based on basic behavioral science and statistics, every desired action from pt A to pt B (e.g. visit website -> buy a product) is a collection of smaller actions that comprise a funnel.

For example, in the funnel of a customer visiting amazon to finally buying a product, amazon loses millions of dollars when initial page load times are 300ms slower within that funnel.

Any added friction between stages in a funnel will reduce the result at the end of the funnel. You add scheduling complexity, physical driving, distributed workforces, etc, and the number of shared lunches are going to drop super fast. Hell, you put 2 onsite employees in 2 different buildings on campus and their chance at a lunch together will drop.

If you or your company cares about in-person collaboration or socializing, you had better foster that behavior and not count on raw willpower to break out of the mold.