https://en.bitcoin.it/wiki/Proof_of_work
If I understand correctly, it's not that proof of work is unnecessary if you want to reach consensus on transaction order without trusted bookkeepers.
Rather, it's that having trusted bookkeepers isn't so bad.
Thanks for all the replies. Yes I intimately understand the block chain and the point. I personally exchanged PMs with Satoshi on some low level technical details.
Qoheleth's paraphrase comes closest to what I'm trying to say.
At the beginning bitcoin was a philosophical problem. How do we do all these things in complete anonymity with everyone being an equal peer. Today, bitcoin and its ecosystem isn't the same beast.
I'm not saying trusted bookkeepers aren't so bad. I'm saying they exist and you discuss them everyday. The Bitcoin community is just pretty pnambic.
http://jargon.net/jargonfile/p/pnambic.html
Ever considered what happens when a block chain fork actually occurs? This:
https://bitcointalksearch.org/topic/alert-chain-fork-caused-by-pre-08-clients-dealing-badly-with-large-blocks-152030
The wizards spring into action!