It felt like what it does is make a higher order polymer, which itself was useful. So, its making feedstock for "more" plastic but not the specific polymer chains of the inputs, or feedstock to make them.

A bit like if there was a mixture of plasticine and play-doh, and what you get out is a composite of both chemically, which it turns out makes lego bricks.

At least thats how I skim-read it.