Part 1 of the article said: "Our new solution needed to be able to linearly add capacity by adding more servers, a property our Postgres setup lacked." From th

Part 1 of the article said: "Our new solution needed to be able to linearly add capacity by adding more servers, a property our Postgres setup lacked." From that, I think we can presume that it was more straightforward to go with MySQL multimaster replication rather than the 3rd-party solutions required for PostGreSQL which are not as mature.