How much blame should go to dispatchers?

In a perfect world, the load would be dispatched with plenty of time to make delivery. But, here's the problem. Drivers goofing off, can't manage their time etc. Then there's weather problems, breakdowns, driver emergencies etc. Drivers not communicating with dispatch present problems too. Some drivers wait until they are 300 miles from the consignee an hour before their appointment to tell dispatch they will be late, when in fact they knew it well before. Or the out of hours scenario when dispatch has a load for them and they knew they had just a few hours available.