... is the players.
At least those with flaming senses of entitlement, or those who can't grasp that anyone else might play differently than they do.
Or those who think they have all the answers to all the issues, but don't.
Or.. well, if I listed all of the people who are the problem, this would be one really long post.
But that is the biggest problem Elite has. After that is just the matter of there not being enough man-power nor hours in the day, days in a week, weeks in a month or months in a year to actually do all the things that need done, that Frontier wants to get done, get it all tested, iron out the wrinkles, and release a fully complete Elite in one go.
Which, ultimately boils down the the biggest player problem of them all: Lack of patience.