I agree. It seems to me that pow is specifically designed to make adding new transactions to the blockchains take a certain amount of time. If anyone could add to the blockchain instantaneously, imagine the same account being used to spend money on both sides of the earth at the same "time". Afaik general relativity says it would be virtually impossible to tell which one happened "first" in a decentralized way. So by slowing everything down, we force there to be a window for transactions to propagate.