[usrusr]

Even more to the point: we can avoid digging coal from the ground, which burns even dirtier than plastics trash.

And even in the lofty goal end state of zero fossils, if it's not a complete collapse back to medieval tech (and population numbers), we would likely end up with biomass based plastics serving as packaging and the like at the upper end of that carbon's energy slope, before utilizing the remaining bound energy in an incinerator.

Biodegradable properties of grown plastics are only a last line of defense against pollution when collection has failed.