That's it ...I'm going to straighten out that old tymer that gave me the analogy.
Your right, I will never say never again.
Unless I really have too.
What I need explained is this...I built a large home for someone, the toilet on the third floor kept backing up and overflowed...not good. We snaked it, took it apart and changed the ring. Same issue.
The reason turned out to be the plumber. When he tested the DWV lines , it was winter. He never took the cap off the plumbing vent outside. Since this was vented by itself, it was the lack of air which caused the issue. The plumber removed the plug...presto chango..a workin cammode. I would think it would have drained from the sink or somewhere else, but the way it was plumbed out..it did not. This was an older type power flush, so maybe that made some difference...only 15 balls instead of 30..could not say for sure.
So It does work for household plumbing also, sometimes, under certain circumstances....but I see where you are coming from also.