[fuoqi]

It's not a myth, it's a basic chemistry and physics. Increase temperature enough and chemical bonds start breaking, transforming complex molecules into simpler ones. Go far enough and you will get bare ionized atoms, i.e. plasma.

But there are different forms of pyrolysis. In my understanding, the company uses lower temperatures to transform plastic into "synthetic oil" (i.e. mix of hydrocarbons instead of long polymer chains), which in theory could be used to synthesize new plastic. Only small part of plastic gets transformed into gas and burned. But this "oil" is much harder to work with than oil pumped from ground, so instead of recycling it fully, some of it gets discarded into environment, resulting in toxic hazard.