What if Flightline would have sold the tickets themseves ? Do you honestly think it would have changed this flights fate ?
I'm not sure I see your point but, no, I doubt it also. But I'm not suggesting that the agency selling the tickets made a lot of difference. Even if that were the case, the Spanish NAA quite probably would have seen little greater justification for doing proper oversight of the flight because it did not take place within Spanish airspace.
But to use the Swiss cheese analogy (with thanks to Jim Reason), the fact that Manx2 sold the tickets was one more slice with a hole. Clearly some of the weaknesses in the system that allowed this accident to happen are more significant than others, but keeping to the simplistic analysis - that is to say, putting some of the dependencies to one side for the moment - plugging the hole in just one slice of the cheese could well have prevented this accident. Of course, on a different day the remaining holes could line up, which is why every weakness that we find needs to be fixed.