An old time rung thing

Found this old-fashioned climbing rung behind an abandoned warehouse today. It has seen it's best days and now it's just a refused piece of wood with no usage. They say these are dangerous so there's been a boom to change all the good old climbing rungs to those ugly plastic thingies. Sounds like some kind of overwarding when ravaging everything because it's "dangerous" with no real arguments - so what's going on?