A leaderless protocol is more complex and requires greater IO and CPU resources per unit of work. This is the hidden cost. The question is if the cost is reasonably offset by higher performance (throughput) offered by leaderless consensus. OP is arguing that the benefit is not deemed worth the cost outside of academia and this is why e.g EPaxos is not adopted.
But doesn't a leaderless protocol also give you more resilience against failures? Or, in other words, can it be that the higher cost buys you not better throughput but faster reconciliation when connectivity is poor? Not in a data center but on a mobile network?
Putting my SRE hat on, I'd generally agree that a leaderless protocol would be the way to go to prevent failures but you will still have to consider the costs involved with running such a system.
I had the same thought. My OP was summarizing the article for GP. My personal [sense] is that RAFT stole the limelight and EPaxos never got any blogsphere love. Few actually even knew about it.