World of Warcraft Arena Guides - Managing Loot in a Guild Guides
Both loot systems work, or they wouldn’t have lasted as long as they have, and would not be around any more. Both try to solve the very real problem of who gets better gear and why. Very simply, and perhaps oversimplified, DKP awards gear based on attendance while Loot Council awards gear based on merit.
There are a few detractors to DKP as well that some players do no like. For example, even though there are addons to track DKP it can be a lot of work to manage a busy guild. There are always mistakes, exceptions, and corrections to worry about. Many guild leaders that run DKP get frustrated with it over time. Also when running DKP it is very hard on new players. It takes a long time to earn points to be able to compete with existing players. Luckily, they will likely have most of the gear they need already.
Lastly, DKP really appeals to type A control-freak personalities. Most players willing to lead raids or guilds, or to take on handling loot for these raids or guilds generally fit the type A classification. Players like the control of knowing who is going to get what when. They like tracking the points and competing on saving, spending, pretty much anything.