*If the system is sufficiently critical, it may be hard to update or migrate it. And if it&#x27;s still safely working there&#x27;s no real incentive to do so.<p>In the very short term, perhaps. But I&#x27;d argue that critical systems are the ones most in need of the ability to be frequently updated and migrated. What&#x27;s going to happen when a serious security problem demands an immediate change, and you&#x27;re not prepared for it? Or the system catches fire, or floods?<p>SPOF critical systems are why so many organisations end up in legacy software hell.