Your dues do go to pay for upkeep, repairs, and renovations of lobbies and all other common areas at a resort. When the resort is both DVC and non-DVC, the costs are shared with the Disney hotel entity.
Think of it as like a condominium in that you pay dues to an association that covers all the costs of operating, maintaining, and repairing a site, both of the rooms and all the common areas, and also pays property taxes for the site. When the resort is combined with a Disney hotel the two share the costs. Moreover for some things like transportation applicable to the site (boats, monorail, and buses), the resort will also share costs with other resorts that share the same transportation devices. Your resort budget annually sent for dues is broken down into a number of categories into which dues go. You have three general categories: the operations budget which is all the day to day operations and maintenance applicable to a site, the long term capital improvements portion which deals with major rehab and repair projects that do not occur every year (e.g., roof replacement, room rehabs done every 6 to 7 years or so, etc.), and property taxes. Particularly the operations budget is broken into numerous categories including such things as costs of administration and front desk, housekeeping, resort maintenance, DVC get togethers and mailings, transportation, security, and numerous others. Some resorts can have cost categories the others don't, such as AKV for maintenance of the animals.The budget needs to follow standard acocunting guidelines for condominiums including that amounts estimates need to be based on reasonably expected costs for the year and not costs plus some priofit for Disney. Disney does have one item in the budget that could be a profit maker but is legal. It is a mangement fee that equals 12 1/2% of the budget excluding property taxes. That percentage never goes up or down but the actual dollrs do go up as the total budget goes up annually. That is not all free money for Disney because it does have to manage the resorts and much pf the cost of Member Services is covered by that cost item.
Mentioned above is that Disney pays annual dues for the points it owns. That is not actually correct. The budget is prepared to apply to all points and you pay your share based on the number of points you have, but Disney does not actually pay its share up front. As the developer and manager of the site, it has the choice, instead of paying dues as other members do, to issue a annual guarantee that for the budget you receive and that is approved for the upcoming year, you will not pay anymore via a special assesssment if actual costs exceed the budget, with an exception for disasters that do destruction to the resort, and Disney agrees to cover any actual excess costs over amounts collected. Disney has issued that annual guarantee for each resort every year DVC has been in existence.The effect of that is that Disney avoids paying dues up front but probably picks up some costs as the year progresses and more so toward the end of the year.