I reuse as much as i can and rinse my recycle, but this is what my municipal told me recently after the Chinese recycle import ban:
1) Many plastics are not good enough to find a buyer: black plastic, clam shell (wrong melting point), dirty stuff (food container), mixed container (plastic coating with paper, etc), etc. They are called dirty dozen here.
2) You can only add up to 25% of recycle plastic without causing structural problem.
3) Cheap oil -> not cost effective to use recycled plastic after the contamination and quality concern
Metal cans are still recycled, and so are clean paper with little to no plastic coatings.
As to why not just landfill and then mine them when we ran out of oil? Because they degrade enough in landfill that makes them just junk, and it cost energy to dig them up, and running out of landfill is a problem they want to solve by recycle.
If they can burn plastic with no pollution, I'd gladly see that. The problem is burning plastic is also not that great of an idea due to pollution. I hope that commercially composeable bio plastic would be the future, it is easier to compose them than to recycle.
The new fad in our area is food scrap collection. This free up some room in the trash for the not recyclable (black plastic, clam shell, egg carton, foam, etc) in the trash.