Hm... This is of course "arguing semantics", which some people for some reason seem to think is a trump[§] card to declare a counter-argument irrelevant, but still: Another way to look at that leads to the direct opposite: If it doesn't yield a useful result, it's not "work" but frivolous waste.
I wouldn't say it's a semantic argument, it's just that the semantics are a bit overloaded. The stored data is useful as a "proof of work" in the cryptocurrency sense, but it's not useful in every other sense of the word, i.e. it's not used to represent meaningful information like like text, application binaries, images, audio etc.
Yeah, back when I was a kid I couldn't come beaming to my dad and expect praise for "Dad! Dad! I dug four holes today and then filled them up again, haven't I done good work?!" I'd have got not only a "That's not 'work', you idiot! Work is useful -- that was wasted effort!", but most probably a clip around the ear, too. And those are the norms I've internalised, so that's how my semantics swing: This whole crypto shit is inherently morally repugnant to me, because it's based on proof of waste.
___
[§]: Eurgh.