But doesn't that in and of itself therefore make it useful? In fact its useful in enabling discussion on HN right now.

The paper was about ideas and exploration about crossing from not-useful to useful and the requirements for that to happen to accumulate a lot of not-useful's for the future to draw on.

This also reminds me of Taleb referencing Umberto Eco's book collection for his anti-scholar/anti-library concept where the 'value' of the library was in the unread books rather than the read ones.

The posts I was replying to talked about 'keeping in the brain-attic tools which may help do work' and 'real, tangible, applicable skills'. That's a different definition than what you're proposing.

Different people will have different definitions of useful. And different people will weigh usefulness differently in determining value.

My point is that I don't need to find some arbitrary definition of 'useful' to cover something in order to find it valuable.