Firstly, there are too many plastics mixed together (and the article touches on that).
There is also the issue that even if you have waste that is made exactly of one kind of plastic, and it's the right one for some application, recycling works by chopping plastic into pieces. This chopping shortens the long-chain molecules that give the plastic some of its important qualities like impact strength. The resulting plastic is inferior to the original, even if pure and homogeneous.
Firstly, there are too many plastics mixed together (and the article touches on that).
There is also the issue that even if you have waste that is made exactly of one kind of plastic, and it's the right one for some application, recycling works by chopping plastic into pieces. This chopping shortens the long-chain molecules that give the plastic some of its important qualities like impact strength. The resulting plastic is inferior to the original, even if pure and homogeneous.