First, a paper written three weeks ago of an unproven currency is a bit of stretch.
Second, I didn't say it was necessary to order transactions, I said that is what it is used for, which is correct. You are replying to a point that I didn't make.
You said proof of work is ABOUT ordering transactions. I was trying to say that it's not. It's used for other things: namely as a way to determine the next miner, like leader election in consensus protocols. It also adds a lot of computation on top of the transactions to show that the miner is heavily invested in the ecosystem and thus serves as an economic incentive. It has almost NOTHING to do with ordering transactions. Transactions are ordered by the blockchain, and everyone has to verify them anyway.
Second, I didn't say it was necessary to order transactions, I said that is what it is used for, which is correct. You are replying to a point that I didn't make.