It might also result result in longer delays once the 3 hours is breached, companies might say that the aircraft that has passed the 3 hour mark can now go to the back of the queue and that others that have some issue can take preference to attempt to get them away within the 3 hours, I know I would if it was my train set.
I think you will find this is already the case, but will be denied.
Additionally, some airlines appear to be attempting to hide behind "extraordinary circumstances" and instead of expediting engineers to apply a fix or provide a replacement aircraft within the three hours, are not in too much of a hurry to do so. Probably on instructions from the company bean counters and/or senior management, thinking of "the bottom line".
They are now about to find out just how misguided this thinking is/was.