All this unknown traffic is because more sites use Amazon's Cloud to host their content.
I put this together to show what I block Amazon wise, yet have very few problems surfing sites.
These are just ones with "amazon" in the string. Lots are without the amazon string but too much work to sort out.
an example would be 184.108.40.206 which hops to Smtp-fw-9101.amazon.com according to http://www.robtex.com/
I've got a lot of links with amazonaws.com blocked, amazonaws.com appears to pertain to Amazon's cloud service.
It's much more involved for me as the above just pertains to Amazon. I block all links that I shouldn't be linked to.
FaceBook and Google are two others that are a B!tc# blocking new links to, but block them I do and still use Google
as a search engine, email other Google services with no problems. Facebook I've no use for.