On the other hand, I think a kind of relation between prize of an operation and its energetic cost would be beneficial (like ---as an example--- forcing an operation to compute a hash of proportional difficulty, or whatever). But this is a different problem.
I’m not largely a free market is the only solution person but this is a very bad example of ‘natural’ monopolies.
Even in the old consolidated system you had differentiation between the exchanges in the form of exchange rules which led to Nasdaq specializing in different listings than NYSE.
If you look at the commodities exchanges they were even more specialized and splintered until legal interventions made those specializations less valuable.
It was governmental intervention that made liquidity the only factor in exchange choice.
Those same inefficiencies in the market would be seen at 59 minutes, at 30 minutes, at 10 minutes, but get less and less impactful each time. HFTs basically provide a service that gives you almost instant liquidity and market making, which is valuable to anyone who's looking to act quickly buying or selling.
I remember first hearing about these ideas in the mid-noughties (around 2004..2007), but then again, I was in a technical university with an economics department. The FCA link refers to a paper from 2013, so by that time the topic should have been pretty well researched.
0: https://www.fca.org.uk/publications/research/periodic-auctio...
That is, have a market where orders accummulate in the order book and every, say, 15 seconds, the order book is crossed and trades are made.