Check out Poland 1984. Then see Monteral 1983 and Philadelphia 1986.
Notice the stage lighting in 1984 gig. It's OK, the stage details are visible. Now check POM/SiT show. The stage is dark. The details are not visible. I intentionally did not put Dortmund because it was a double-stage top tier festival so the lighting was superb (and recording gear too, those "Bofors" cameras!)
Seems to me like 1983/1986, as opposed to 1984, weren't budgeted for live shots.
Which is cool, I won't say we knew that but comes out logical. What I did not know is there was a stage. I thought the first "full" stage was Powerslave.
Then again if you think about evolution of the stage set in the 80s, it is quite iterative. They had props and effects and Eddies in Dianno days. They added stage risers for TNOTB. They defined the boxed riser shapes on POM, added a floor and thematic props and details over those risers. For 1984, they made enormous effort on the riser's livery, props and added a backdrop. In 1986 they made riser shapes more complex and then made an enormous effort on the props.
So technically you could say that plumbing was the prototype for Egyptian theme, how the stage is shaped, laid out, etc. The top margin of those riser boxes include a window and that window includes this "plumbing", or the stage theme. If you check out stages throughout their history, even stuff like En Vivo, you'll recognize this design pattern. The leap was big but I still think this bunch of pipes has some historical significance.