[alt text: first, there's text over a happy Albinauric from Elden Ring saying "me when I thought recycling would save the world. second, there's text over a sad/depressed Albinauric from Elden Ring saying "me after I found out that plastic corporations invented plastic recycling to put the responsibility onto the consumer even though they knew plastic recycling was both chemically and financially not feasible, and now I have plastic in my brain, lungs, and testicles".]
because they were lighter and more compact, transporting them burned less fuel. so they were 'less polluting'