I guess it would be hard to do chess-by-mail via Amazon warehouses/shipping. And I can't order a bank statement from Amazon.

Of course. One does not replace the other.

It's most like I think we should nationalize the Amazon warehouse system and put under the post office.

Perhaps both are valid interpretations of the US constitution's postal clause, "To establish Post Offices and post Roads" even!

And therein lies the problem with content addressable networks: they make no sense in the economic world of the internet, where data transport and storage is not free, they make sense in a world owned by a single corporation.

Huh? The same efficiency gains should apply to both applications of content based routing.

I do think there is a natural monopoly, but that is just and argument for nationalizing things. (And agreements like there being one IP protocol or whatever.)

Some might argue they fail to do the "thingy matching SKU" effectively these days.