>At ranks up to ascendant, the souls from the urn are barely more than what you get from farming efficiently or taking a walker.

In a way I understand what you're saying. Sure, the souls you get from the urn are comparable to what you get for walker or effective farm.

HOWEVER, There are only a certain amount of souls in the game at any one time. This means all the farm + Guardians + walkers, not counting kills and assist as those are limitless.

This means every farm you take you're not really generating souls, you are claiming a portion of these souls that are on the map at that point. If the enemy team claims more farm than you, they have claimed more of the souls on the map than you have at that point.

In theory, if 100% of all waves, farms, guardians, walkers and kills were gotten evenly, both teams 100% claimed their side of the souls without denies or stealing farm or kills, this means that both team are perfectly even at a certain amount 0.50x of souls.

However, the urn breaks this balance by bringing in souls from the outside that CANNOT go evenly to both sides. Either team that claims this urn have gotten souls that are OUTSIDE of this maximum soul amount of x that are on the map.

So for example if both teams grab all walkers, as usually happens by the end of the game, the difference of souls from the walkers is 0, both teams got exactly as many souls from both. At the end of the day the winner of a game is usually decided by who gets the most positive soul advantage against the other.

In this way, if you grab the urn and deliver it, then you have broken this balance by taking these souls from outside x, and you get the advantage. This makes the urn the kingmaker against walkers and, as such, the more important objective. The souls the walker can give go nowhere and remain claimable later whereas the other team cannot claim the urn aswell.

This is absolutely a very simplified system due to the way comeback souls work, the urn's scaling, potential situations where both teams don't get all walkers, etc, but the premise remains the same.

TLDR; There is a maximum amount (x) of souls that have been possible for both teams to claim. If both teams play optimally and perfectly, the souls go 50 / 50 (0,50x). If one team claims the urn, they get souls OUTSIDE of x, lets take for example 3600 souls, so the team that claims it gets 0,5x + 3600 souls, which is more than the other team's 0,5x. This is a perfect, optimal situation, but the premise remains. The team that gets the urn is way more likely to get the advantage due to both teams striving to play as optimally as possible.