ARURF is bad because you don't have bans
That's it. That is the reason.
If you allowed us to remove things like fucking SHACO. Then ARURF would be fine.
EDIT: Also Sion's passive should be normal in urf. not buffed. If you are playing Sion the optimal strategy is to build tank and just run at towers. you will actually win. its hard to lose playing int at towers sion