I guess I don't understand the purpose of a Gizmo in an AG pool.

Last year when we closed, we removed the pump and took it in the house. We lowered the water to below the skimmer & return, removed all the hoses between the pool, filter and pump to save them from damage from any freezing water that may be in them. This left the skimmer with a drain hole in the bottom for any water to run straight through. I would think that by using a Gizmo, it would allow water to pool in the skimmer and risk damage.

What am I missing?