I agree. It's not the airlines fault that there was weather problems. But it sounds like the airline has no blame and that is incorrect.
IF the delay was 1 hour, I agree, its weather, but 6 hours? Basically there is a point to everything. At some time into the delay, common sense has to kick in and tell you the weather is not clearing. After an hour, why not go back to the gate and then reboard four hours later. This way the plane will still be ready to use its slot and the passengers will be happier as a result.
To answer the other question posed by TX_flyer. No he did not have even the slighest idea there was a weather problem. He was early to EWR so he went to the gate and asked to get on the earlier flight. NO mention was of the fact that the earlier flight was scheduled to depart at 12 and it was then almost 4. In fact, the read-out above the gate showed a departure time of 3:55pm. The check-in person should have made him aware.
He is not blaming the airline for weather or the delay, just the way they handled it. Remember that Customer First stuff?