I know its compleatly random and probably not related at all but honestly I think they're kinda similar.
an 0/10/0 teemo is pretty useless, but he still has his blind and his mushrooms so hes not useless, similar to Soraka who even when feeding is still good late game.
That's pretty much why Soraka top is working.
You don't need to win lane. You don't even need to do well. Her utility and global presence is more than enough to help the team. Her sustain and poke let her avoid feeding, and that's all she need to do to be more successful than a standard top laner.
its why Shen is also very good top, or Karthus if its a safe lane.
