If the toilets at all those firms started operating in reverse, very little would get built. The conclusion is that plumbers are extremely important, not that plumbing is de facto engineering.
Plumbers build all the pipes, but one of the aforementioned professional engineers created a drawing of where they would go and how the water and sewage would move through the building.
Plumbers build all the pipes, but one of the aforementioned professional engineers created a drawing of where they would go and how the water and sewage would move through the building.