Crowded, rich countries that responsibly burn garbage & waste still have a serious issue with dioxins generated by burning plastics. You can filter some of it, but usually areas around these plants have much higher than normal dioxin levels.

That said, I like the balance in your comment about the known effects of microplastics. At the moment, it is just a hype story. Honestly: No one really knows, but we should continue to seriously monitor and research the issue. I have heard that stretchy clothing (aka "ath-leisure") causes a lot of micro-fibres to be shed during laundry. This is simiar to microplastics, as most ath-leisure is made with synthetic materials that are essentially refined oil (as plastics).