They eventually admitted that they were writing it as they went. And JJ Abrams basically stopped having anything to do with the show after the 2nd or 3rd season. New writers kept showing up and pushing totally obscure plot lines and not bothering to tie up loose ends written before they were hired.

Then they tried to pass it all off by saying the show was about the characters, not the plot. And that as long as all the characters stories were wrapped up, the plot didn't matter. Nothing about the final season made sense, and were by far the worst episodes. For instance, the episode about Jacob's back story was literally the worst episode of all 6 seasons. The writers had promised us on the LOST forum that this episode would answer all our questions about Jacob, Smokey, how Locke turned into Smokey...all that crap. All the episode did was introduce yet another insane character that they forgot about the next week.