Because I served, I will resist
With 3-5 players you're often making moves that give you 10 points and give other player 10 points. It's sort of cooperative/competitive. With 2 players you'll often give yourself only 2 just so the other player gets 0. It's zero sum, a bit trickier, and a bit nastier.
This totally makes sense.
I normally don't like zero sum in 2p games, but this one is the exception. It's probably because it's an economic game and that so many other zero sum games have a take that mechanic or at least a take that vibe which I loathe with only 2 players.