I agree with you.
I don't house my snakes together so I don't know what they need to live healthily together. You have kept snakes together and you do know.
I know the "risks" associated with keeping ball pythons together so that is the information I provided. I understand many of these "risks" are just scare tactics.
So I should have said something like. "Yes you can keep ball pythons together but I have never done it so I don't have any information that can help you. I think it is healthier to house my snakes separately"
It takes a lot of money and time to set up a big enclosure like that and to keep it properly heated. It is a big project, much bigger than putting a snake in a tub. Some people, like Robin said, are really just looking for a way to cut costs, and putting multiple snakes in an enclosure would increase costs, in my opinion.
I am not denying anyone information, I just simply don't know how to properly house snakes together since I have never done it.