I still remember a few years ago DL advertising they had the "least cancellations" amongst the US3. Turns out it was because they just kept having rolling delays (12+ hours sometimes!) instead of just canceling the flights.
I don't know about you, but I would prefer a canceled flight rather than sitting around for hours and hours with rolling delays, only to be told many hours later the flight is canceled. That is just downright disrespectful
Agree with rolling delays, but an overnight delay is better than a cancellation by a long shot. Every passenger still has a seat on a plane after that delay - when a flight gets cancelled, it means every passenger has to figure out a new way to get to their destination. And you always still have all the same options you had with a cancel (if there is a better flight, take it!). Typically those 12+ hour delays had an initial 2-3 hour delay and then get the dreaded overnight push for crew rest - it wasn't like it was typical to have rolling delays for all 12 hours.
Yes, this was a tactic to reduce cancellations, but even with these long delays Delta was able to do this while still having the best on-time rate back in the "golden age". Furthermore, it still required getting new crews, planes, and so on into position the next day as that crew wasn't supposed to be there the next morning - so it isn't a free lunch for the airline either.