Only 6% of the world's petrochemical usage is to make plastic. If we decarbonize everything else but merely burn every gram of plastic we produce, that's a win, both from a climate change perspective and from a plastic waste perspective.
Proper incineration is probably the most reliable, most effective way to deal with human waste.
Well made and managed landfills are also perfectly capable of dealing with human waste, but they are a long term project, and there's a lot of time for a dumb management or politician to decide you don't need to fund it as well and now a hundred years of hard work to protect the environment goes down the drain when your now improperly managed landfill is basically a superfund site.
There's less chance for one idiot to do long term damage with incineration.
How is it ideal to increase the amount of CO2 in the atmosphere even further?