Did you or anyone else has actually observe any such processes? I mean employees A and B meeting at any place which is not a workplace or any of them (because meeting at workplace means one of the pair has come specifically to another, and that is mostly equivalent to calling that person by phone, on full remote) and there spontaneously talked about work topics generating previously unheard idea useful for the company?

If the and answer is yes, then what was the rate of such encounters per number of employees?

And finally - honestly answer yourself - does this minuscule probability worth the ~30 full awake days in every years of life, of every employee? (2 hours commute per 250 days in a year, then divide by 16 awake hours per day) For me the answer is obvious - it is not even remotely equal in value to such a gigantic time waste. If that super brainstorming even real at all. Personally I've never observed this.