something like storing a blog text for thousand years, especially after the author passed away where the blog could not be maintained by the author.

no this is not helpful for the flow of the system, more like supply tracking, logistics, farming..

Except it has no power over the physical world. Just as one can lie on a ledger and say slave labor did not make these resources, so too can some one lie onto a block chain about where resources came from.

The chains can only really enforce protection on their own currencies, no?

It was not about the initial data but the overall coverage and self management. How many businesses still have their own ad-hoc half manual uninteroperable process and apps ?