Dave; One explanation might be ... I think that some people don't really want to sell an item ... but are simply fishing for what an item is worth and so they put unrealistic reserves on some items.

If the item does sell at that inflated reserve price ..., they figure maybe they got top dollar for it.

They also now have a listing of other would-be serious buyers after the sale is over who have made less-than-reserve bids on the item ... which may be close enough to the reserve to dispose of duplicate items the seller may have in inventory (or access to addtional items) at the slightly lower bids.