We have a lot of knowledge on how to literally burn plastic and not pollute anything- waste really doesn't have to be an issue.
The micro plastics that studies find in the human body are probably from sources no one cares to address- acrylic paint, tires, polyester clothing, things that are constantly being ground into nano particle size bits that are omni-present in all environments (and no one even considers getting rid of).
If you live in a first world country the ocean plastic isn't from you- if you drink from a plastic straw or not it probably doesn't matter. That plastic is most likely from fishing nets and from a few countries where people throw their waste directly into a few rivers.
People would rather focus on shaming those who don't sort their trash and drink from plastic straws.