Yes, that CAN happen but in 39 cruises, 25+ times to WDW, many other vacations, I've never even waited an hour for security, let alone close to 3 hours. If anything that catastrophic happens, well then I guess I'll miss my flight. I probably won't be the only one though. It probably happens every day and we'll pay some fee to get put on a later flight.
Otherwise, I'd rather have those several hours at home to unpack, do laundry, and put the luggage back in the attic before returning to work.