But it doesn't have to happen at the exact same time? Limit orders exist, no?
Sooner or later (spoiler alert: sooner) someone would put it on the Internet, and it would be unregulated, at least at first, and the insiders would do even better than they are now.
You should read up on the early days of ECNs, Island and Archipelago and what not. Alternatively, you could look at this exact script being played out in crypto right now.
You are begging the question. Why should a market reflect that? Why is that preferable to a daily auction (throw in a stochastic cut-off time to thwart HFT even more)?