The Era Of Unlimited Everything: Unlimited Materials & Unlimited Money
In my opinion, the true wonder material is oil. Of course, plastic is made out of oil, thus what you explain about plastic applies.
Without oil, there would be no industrial agriculture, no mass transport of goods and people. Without oil powered machine, building houses, or mining materials for your electronic devices would be orders of magnitude more expensive. People could not buy products made far from their home region. The standard of living in rich countries would not be very different from poor countries.
Bad news : oil is not unlimited (unlike credit). It will be very hard to replace it once exhausted.