Why isn't Shen jungle popular

I have to say that i'm actually amazed that Shen jungle isn't popular. He has very safe clears since he takes little damage and he has the best counterganks in the entire game. Once he hits six, he can ult into any gank and turn it around pretty easily. I have been able to wreck enemy teams doing this.

Not to mention that he can get and split push all day. Seriously, why isn't he played more?