The Orzhov welcome you. Please leave your belongings with the Obzedat. They are not yours anymore.
Hi, I'm a european crested tit, and a very small punk rocker!
I'm playing a 3-player game. It seems you can easily get infinite souls by farming. On the three tiles on the way to the miniboss, we can earn 18 souls. Then we can use a spark to start over. Now we spend 6 souls to get that spark back, go earn 18 more again, and repeat indefinitely until you have the best equipment.
What am I missing here besides this being pretty boring?
You miss nothing and it is indeed incredibly boring. These rules do nothing except make the game more of a grind than it needs to be. After trying it two or three times I gave up on Dark Souls completely.
So do yourself a favor and don't try the campaign mode as written.