I don't understand people sometimes. You find inexperienced travelers, flying on perhaps the busiest day of the year, or otherwise during a high-traffic season like the holidays, or during winters where snowstorms might happen, and they encounter a flight delay. They moan and complain about it, and immediately they declare that "I'm not going to fly [insert airline here] again!" Sometimes these people make me scratch my head and think how they have a large sense of entitlement. Well, just travel some more and you'll soon see that operations are not always smooth.
See, typically it's these people who just fly once a year, who can say that they'll never fly a specific airline again, after a simple delay. Sure, your plane might have been delayed for 6 hours because of a mechanical issue, or because of the weather, but come to think of it, it's better to travel safely than travel dead, right? If you have more travel experience, and therefore increase your flying experiences, then soon enough you'll realize that airline operations are more complicated than that.
Let's take the US travel market. I once flew American Airlines flying from Buffalo to Quito via Chicago and Miami. On the way back, my Miami-Chicago leg got delayed, to the point that I wasn't able to make my connection to Buffalo. The next flight was leaving the day after, so American Airlines put me in a hotel and gave me some vouchers.
In another incident, I was flying United Airlines from Tokyo to Buffalo via Chicago. Somehow one of their other flights from Tokyo was canceled so they were transferring other passengers to other flights, including to the one I was in. Because my incoming flight (with Japan Airlines) was late, they gave my seat away, and when I got to the gate, they told me that I either can take a different seat (a middle seat) or I can opt to fly the next day. I opted for the latter, so they gave me a hotel in Tokyo as well as some vouchers, and some credit I could use for a later flight, and they put me on a higher travel class for my flight the next day.
I could easily imagine people who would immediately say that they won't fly American or United again because of these incidents. And yes, sometimes, incidents like these happen and you don't get compensated. Sometimes your flight just gets delayed for 6 hours, or gets a diversion because of a mechanical issue. If only everyone would look at the bigger picture, then one would realize that these incidents while negative and unpleasant, actually are rare, and most flights go smoothly. In a normally distributed set of flights, chances are there is a small number of flights that will not go smoothly. And that is normal. No need to declare that you won't fly with a particular airline again.
I am not saying that it is totally unacceptable to opt not to fly with a particular airline. Heck, even I have my set of airlines I avoid. All I am saying is that the low-probability negative event you experienced when you flew (which in itself was a low probability event) is not a logical reason enough to blacklist a particular airline.
The problem is, not everyone is logical. Too bad.