No, it is a suggested configuration, not the suggested one. And recommending three nodes is not that uncommon for distributed systems, because you cant have a quorum with only two nodes. Some users are more concerned with handling 10s or 100s of servers than having single-server durability.
That said, for most users two servers are fine. Other users don't need any replicas at all since they do a nightly dump from a stored source into mongodb, or they just take regular backups. There are many ways to achieve system-wide durability, not all of them require the database to be durable.
That said, for most users two servers are fine. Other users don't need any replicas at all since they do a nightly dump from a stored source into mongodb, or they just take regular backups. There are many ways to achieve system-wide durability, not all of them require the database to be durable.