Fish tanks are for fish...Not ball pythons?
Some people prefer to have their snakes in a nice enclosure where they have room to roam/climb and where it looks more natural. Not in a rubbermaid container with newspaper, water and a a hide.
I understand some people with multiple snakes/breeders might have to do this but dont tell someone with one or two snakes that their snake shouldnt be in a tank.
Then again, thats just my opinion. But my snakes seem to be happy in tanks.