this doesn't qualify as a case of reductio ad absurdum because the original argument was not "why don't we allow duplexes?" but "why does the collective have a

this doesn't qualify as a case of reductio ad absurdum because the original argument was not "why don't we allow duplexes?" but "why does the collective have a say in this at all?" and the answer to that is "because of negative externalities"