Rec-league hockey requires an ice rink and time on it. Ice rink time is highly demanded and you may be getting it at 6:00AM or 11:00PM. You also need to coordinate teams at those times. And if you want any practice time-you may be getting that at 3:00AM in the morning (not joking).
And, for all of that, you get the joy of shelling out lots of money for the privilege of using the ice on the graveyard shift.