>The reason is because although it is not technically difficult to "unhook a toliet" as you say it is even easier (especially now with the advent of Home Depot and Amazon selling all manner of "plumbing contraptions") to inadverntly create a potential cross conection.

Please tell us how one can screw up hooking up a toilet so badly as to create a cross connection. It's not easy to confuse a 3" or better closet flange with a 3/8" compression fitting, and it would be pretty obvious to anyone who tried it.