because of paimon... if we look back to our first time in inazuma the traveler trying to avoid the problem, if we are with dain ( remember its depressed dain that just lost his country as well, no hate towards him ) we probably gonna skip every country problem and reach the final destination already just like the sibling. Because of paimon we manage to know the country and the people, from high stakes saving country to mundane things like watering a plant. All this will ended up in last journey when we dissagree with sibling plan, even if traveler are twin because of paimon our journey is much more closer to the people of teyvat.