I think that even in parties that don't have a definite leader, i.e. a casual or unofficial one, can still have a leader who's decisions are final even though the other characters are not quote-unquote required to follow them like in the drow example. It really depends on how the leader RP's his relationship with the other players. For instance, if the leader sees his companions as equals, say with Tanis in Dragonlance or Drizzt his books, or if he is still the definite leader but respects the knowledge and veiws of his subordinates, Captain Picard, then the group should work fine for D&D. In this case the leader gets the final decision making ability.
The other way the leader could go is the way I feel is the only way to really play a Lolthite without the Goddess stripping the Cleric of her powers for being so weak. That is the role of unquestioned leadership, but also of superiority in every meaning of the word. A brillian tactition General who values the advice of his aids, is the unquestioned leader, but sees the value of others.
A Drow Cleric would see a meer male that dares to even speak with out being spoken to as an outright insult, and one that presumes to tell her what to do, as an infidel who should be punished (read: killed). Even with other characters with one or two levels in cleric, the character with the most levels would be seen as the superior, and would see her self as such (assuming levels OoC equates ability IC). And you always have to worry about a weak willed Cleric that lacks control of her males loosing her abilities because Lolth has found her weak.