Maybe just my experience, but an engine is running poorly, pulling the plugs and doing a compression test you find it’s bad, then you go to the junkyard and pick up a running one for half what boring and piston replacement would cost… out goes the old engine without plugs.
In the case of engines in cars, it could be from the time when used cars were cheap? I remember junking a Pinto with no compression and replacing it with a rusty but running 1965 Mustang for $75 and the scrap pinto. That pony gave me 3 years before it wouldn’t pass inspection…