Right. Which is not what I was talking about. This was about how a PoW chain would become useless if there was no cost involved in making blocks, ie, if the "W" part was missing. It would allow anyone to add blocks. There'd be no way to distinguish forks from each other and decide on a canonical one. Being able to agree on a particular fork as being the "valid" one in a decentralized manner is the fundamental secret sauce of what makes cryptocurrency work. All the various protocols boil down to ways of solving that one particular problem.