I think most diplo games, while they may not emulate real-world politics, must try to emulate politics in some way. Whether it's playing two people against each other to try to make your position better, making everybody in the game see your enemy as "the bad guy", or making complex "land swap for alliance" deals, ordinary non-rp diplos have to try to emulate politics.
These are choices, but there's no grounds that they must
be used. If folk do not want to use, they do not have to.
With roleplay, two large nations that would rampage unchecked in diplomacy might be wary of the other because they are "Elves" and "Orcs", and thus natural enemies, or whatever.
Or just since there is only going to be one winner, or that one is growing faster than the other. The Cold War was not about "Elves" or "Orcs" and, politically, not about "communism" and "capitalism".