Indeed, the airline I worked for would not have been able to operate a significant part of its operation if an alternate was required for all operations to remote/island airports.
So, what was the fuel policy - island reserve, plan to a PNR etc etc? I'd be very surprised if a responsible operator didn't have contingencies or options in place, particularly at the planning stage, and hadnt kept revising them thereafter as the flight progressed.
And therein lies the difference, there was an option at the planning stage and that was to take more fuel. There were options during the flight which have been discussed at length in this thread. In short, an apparent mindset that a landing at the destination was assured so no need to keep formulating a "plan B" as the flight progressed.
Id be very concerned if your airline had asked you to put all your eggs in the one basket before you even got airborne but in this case ..........