It slows deployments, it needs to be retested from time to time as domains move / expire, and on balance has the potential to cause more pain than it solves for

It slows deployments, it needs to be retested from time to time as domains move / expire, and on balance has the potential to cause more pain than it solves for. It defends against an edge case (domain owner being irresponsible) at a cost (everyone else gets slowed down). It's a judgement call, largely.