While I'd agree with the general stance of avoiding MongoDB for any new project, I find the statement that postgres always gives better and faster solution dubious. They don't really solve the same problems. If you happen to really need horizontal scaling, actual HA (not failovers) or documents with many field-level atomic operations, MongoDB might still be a better fit than postgres. For on-premise hosting, not having any HA out-of-the-box can be a major painpoint.