Because incineration or proper disposal is not the problem. Gathering and segregation is. Plus, launching that sort of payload is going to be insanely costly.

The sheer volume is manageable as it currentlyis, but it’s spread out so much that collecting it properly is going to take a lot of time an effort.

The Great Pacific Garbage Patch is a bit of a misnomer, as it’s more of a vague area in which trash tends to collect. It’s not like an actual continuous patch that you can easily attack with a net.