PoW is by definition an expensive-ish computation.

Sometimes the result is used for something. Then it's not wasted.

What we're seeing is result that's not used for anything, only to slow down access indiscriminately, to burden LLM bots so they don't burden the sites so much. It's entirely wasted computing. How can there be any doubt about that?

This kind of waste multiplies and accumulates, whether or not one keeps track of it.