In support of the idea that the island is purgatory by Winston

Did anyone else catch on to the idea that all of the people we didn't see on the plane or on the island - the people who weren't transported into the 70's: Libby, Shannon, Anna Lucia, Eko, Claire and whoever else amongst the people we didn't see whose names are eluding me - were all people whose problems were resolved at one point or another throughout the previous 5 seasons? Essentially they were able to overcome whatever it was that was bogging down their ascension into heaven, whether it was through death, enlightenment or other means, and all of the people who were still on the plane or who were still on the island - Jack, Kate, Rose, Charlie, Sawyer, Hurley etc. - were all people who were not able to overcome their problems, sicknesses or dilemmas.

It is not necessarily to be taken as an actual purgatory, but the idea that the island is some sort of metaphor for the afterlife or specifically purgatory is longstanding and the first shot of the episode was literally an underwater underworld of death, 40,000 feet under the ocean.

It is an interesting idea, if anyone can further prove or disprove it then please do so.