For Doom specifically, which uses a P2P networking model, yes, that probably would have been technically superior. It would have taken more work, though -- this

For Doom specifically, which uses a P2P networking model, yes, that probably would have been technically superior. It would have taken more work, though -- this demo was thrown together pretty fast. Durable Objects could still have been used for setup, yes. Most modern games use a client/server model, in which case the possible role of Durable Objects is a lot clearer.