  In the high-stakes race to develop more scalable blockchains, some platforms
(Binance, Cosmos, EOS, TRON, etc.) have adopted committee-based consensus (CBC)
protocols, whereby the blockchain's record-keeping rights are entrusted to a
committee of elected block producers. In theory, the smaller the committee, the
faster the blockchain can reach consensus and the more it can scale. What's
less clear, is whether such protocols ensure that honest committees can be
consistently elected, given blockchain users typically have limited information
on who to vote for. We show that the approval voting mechanism underlying most
CBC protocols is complex and can lead to intractable optimal voting strategies.
We empirically characterize some simpler intuitive voting strategies that users
tend to resort to in practice and prove that these nonetheless converge to
optimality exponentially quickly in the number of voters. Exponential
convergence ensures that despite its complexity, CBC exhibits robustness and
has some efficiency advantages over more popular staked-weighted lottery
protocols currently underlying many prominent blockchains such as Ethereum.
