Nope.
I wasn't there so can't speak for this specific reason in this case, but there are hundreds of possibilities
(but my background is airline operations, specifically working for AA at the DFW Operations "tower", then System Operations Control (SOC) back in the 1980-90's)
In general:
- being deplaned/delayed/gate change/whatever for "mechanical" reasons doesn't mean it's your ("your" = the OP's) airplane with the issue.
- the plane with the "issue" might not be grounded per se, it just can't be dispatched on its current route.
So ... let's consider this hypothetical scenario:
- Your flight's airplane is in perfect shape. No write ups, nothing placarded as "inop". Your pilots have completed their initial checks and so far everything is "go".
- Weather en-route and at your destination is also perfect. It's going to be a perfect flight and vacation !!
- 2 gates down, leaving about the same time as your flight, another plane also looks good. However; on start-up, the pilots received a "fault" indication on the weather radar.
- The forecast at that 2nd plane's destination calls for a slight chance of thunderstorms around the flight's ETA
- this 2nd aircraft can not be legally dispatched to it's scheduled destination without repairs. Maintenance knows what this "fault" message is and it's a 6 hour repair.
- this 2nd aircraft can be legally dispatched to your destination as weather radar is not needed.
- your airplane can legally be dispatched to the destination with possible thunderstorms in the forecast.
- it's swap-a-roo time. Even last minute. In the "big picture", 2 (or 3 in your case) 1.5 hour delays is better than one 6 hour delay.
Another generic scenario to consider at hubs
(hypothetical only ... I did not research the flights in your case, but it's a concept that's common at hubs ...):- assuming the 3 flights involved depart PHL on the same connecting "bank" of flights, let's also assume those 3 planes are scheduled to turn around and fly back to PHL. And also all 3 on the same "arrival bank".
- the flight farthest away from PHL (the MUC flight) is the least able to absorb a delay on the inbound. Let's say the inbound needs to arrive on-time to confidently make the "turn-around" departure an hour later.
- the destinations closer to PHL (IE: DUB & BCN) can easier absorb an inbound delay because the inbound planes typically sit on the gate awhile before returning to PHL (to arrive the same approx time the MUC flight arrives)
- it isn't a matter of one city being a higher priority than another, it's basic geography/distance. Off topic, but the reverse is true for ATC "flow control" delays ... close in airports are delayed inbound to the hub because they're not airborne yet ... the longer flights are already airborne thus allowed to continue.
The bottom line is that airline operations are complex. To maintain the impeccable safety records that airlines do, means that operational decisions are going to be made that negatively affect the customers. It's a fact of life. Contrary to what many FT's believe, these decisions are not being made to ensure
your flight has minimal impact. The big picture is that
all flights collectively need the least impact possible. So yea, the airlines will issue a gate change (actually an aircraft re-assignment) to your flight even though it is already boarding, then issue a delay even though it isn't your plane that is "broken". This ensures that tomorrow (and all other things being equal), the MUC flight (who was reassigned the "best" plane due to the tighter turn-around) arrives PHL with a slight delay, while DUB & BCN arrive on-time, despite yesterday's departure delays .... this vs 2 of the 3 arriving on-time and the 3rd being a complete mis-connect due to the 6 hour delay departing PHL yesterday.