So....if you got on the bus prior to your assigned bus, you left your resort 3.5 hrs prior to your flight. It's only 30 mins to MCO, after the last stop. Even if you were the first stop, and then stopped at 4 other resorts (which doesn't happen very often, 3 seems to be the norm), you still should have arrived at MCO with over 2 hrs to spare...which is exactly when MCO recommends you arrive. I usually arrive 2 hrs prior to my flight, sometimes a bit earlier, depending on the stop I am along the route.
If Disney had done what they were supposed to do, and got a bus there, then all would have been fine. But, if the OP had known that there would be no bus coming, they could have gone to the food court and had a bite to eat. They could have hit the gift shop, or even slept an addtl 30 mins.
What you are 'missing' is that this family was told a time to be there, waiting for the bus...and they were. BUT...DME neglected to send a bus out for them...so, they were left standing for about an hour, waiting for DME to send a bus that they would be allowed to board...since the bus that arrived 30 mins after their allotted time wouldn't let them on board!!! So, they basically wasted over an hour of their vacation time. Sure, that time would have had them at MCO if they had been picked up...but, they could have gotten something to eat at the airport and relaxed a bit, rather than standing there, worrying about whether or not a bus was coming. Let's remember...they had been told that the next bus would combine passengers from the two time slots...but they were denied boarding by the driver. So, more angst. Now, you have at least one family, and probably more, worrying about whether or not they are going to make it to their gates on time. And that shouldn't happen. That is not how DME was designed!! It's supposed to let you finish your WDW stay as stressfree as possible.