Good point. The RPM part is easy for them and a 'reprieve'. I just remember back in the old turbo days and admittedly now they have serious electronics to make them work. Making an engine last back then for A race was amazing. Ask Renault especially!
But they never wanted them to last more than a race back then. They tuned them until a hair from death..and since they were being rebuilt after the race anyways, they just needed to last a single race...