Since the article states that they're using Raft and not ZAB for the consensus algorithm and leader election, it must be less prone to bugs when it comes to electing a leader. Since Raft is easier to reason about and the leader election process is more straightforward (Raft minimizes the chance that any two nodes will be candidates at the same time and thus avoids starting multiple concurrent elections).

Just adding on to a nice response from abronan, our internal protocol also does some optimizations when it comes to leader election, e.g. Pre Vote protocol (https://github.com/eBay/NuRaft/blob/master/docs/prevote_prot...)

Also, we apply many different faults in our Jepsen tests which are run 3 times a day and we never had a problem with leader election. I know this doesn't confirm that there is no bug in it but it's pretty reassuring I would say.