I've never felt jerked around with any of the majors when it came to rebooking travel. They can't conjure up an empty seat that doesn't exist, but I've also never been required to pay a higher fare for them to take me on the itinerary that I originally booked.

Delta in particular I think is quite good at recovery from irregular ops (at least for their higher tier frequent fliers), but on the few instances with other carriers, I expect (and have received) decent and fee-free service when the airline cancelled a flight or missed a connection due to airline fault. I fully expect to have a crappy experience on Spirit whether or not they cancel the original flight.

It does seem like post-Covid all of the airlines are racing to the bottom for quality.

I've had canceled flights before but no other airline has ever forced me to rebook effectively the same flight at double the rate and wait the 8-10 days for the refund on my original flight to my credit card. Back when I was a brokie (you know, Spirit's main customer base) that kind of shit would have been trip-ending.