The amount on the ISS is likely extremely tiny compared to any waste produced in the manufacturing of mass consumed goods
A very tiny amount burning up at great speeds over hundreds of thousands of square kilometers is much more diluted than anything feasible on an industrial scale
It's likely cheaper to dispose of it in a controlled environment than it is to properly dilute it across the globe. And it's impossible to check that the "dilution" won't just end up being dumping it all in a single spot in the ocean devastating ecosystems
A very tiny amount burning up at great speeds over hundreds of thousands of square kilometers is much more diluted than anything feasible on an industrial scale
It's likely cheaper to dispose of it in a controlled environment than it is to properly dilute it across the globe. And it's impossible to check that the "dilution" won't just end up being dumping it all in a single spot in the ocean devastating ecosystems