Wrong, because even if the exchanges pick a chain that is completely ridiculous in terms of rules, say they permanently limit the tx throughput for the entire world to 3, or something absurd like this, and the exchanges and users who can see how absurd this is sensibly opt out of mining or transacting on that chain, the profit for defecting is great, because mining is a zero sum game.
As long as some suckers are trading actually liquid assets for the instruments on the sabotaged chain, it is economically rational for the miners to mindlessly rubberstamp the rules of the chain.
As long as some suckers are trading actually liquid assets for the instruments on the sabotaged chain, it is economically rational for the miners to mindlessly rubberstamp the rules of the chain.
Which is exactly what we have.