Because Dragon Soul buffs are so powerful that the game ends within 6 minutes of it being taken. In all 9 games a dragon soul was taken, that team won. 3 of these were games were dragons were even until the 4th.
Ocean soul? Oh, hey, the enemy team is just too difficult to kill.
Mountain soul? Same thing.
Infernal soul? Oh we get poked out by even crappy poke.
Cloud soul? We no longer have any choice about fights. Someone presses R and the fight is on because they have 40% increased movement speed.
I think that - due to these being permanent buffs - that maybe they should be weaker. Like, maybe a lot weaker. Like about half of their current values.
The last game I played, which was on my smurf, my team actually surrendered when the enemy team got their 4th dragon (Mountain / 3x infernal).
Not sure I want to see elder spawn, since it seems to be bugged, but it might be nice to entertain the possibility of not just losing outright if the enemy team gets dragon soul.