It's a pity the parent commenter led with that point. Their second point, that the overwhelming majority of ocean plastic pollution comes from those two sources, remains valid (albeit I'm not sure if it's actually true but it certainly seems feasible).
To their second point, blaming the Philippines for dumping our ‘recycling’ in the ocean is a little bit like blaming African countries for burning our e-waste. We can’t pretend you can generate pounds of single-use plastic waste per person and have the problem disappear when you put it in a blue bin. Recycling is a lie invented by the packaging industry, and the reality is that we export the problem in bulk to the developing world, who inconveniently happen to share a planet, physics, and economy with us. We’re the ones buying the plastic to begin with, and it’s only right it washes onshore back here so we can’t pretend it doesn’t exist when it hits the bin.