[benbjohnson]

Author here. The comparison was meant to be about how Postgres (or any client/server RDBMS) is typically deployed. Yes, you can deploy Postgres on the same machine but I wouldn't say it's common. Maybe I could have expanded more on that point or simply referenced client/server architecture rather than Postgres so it didn't seem like a straw man argument.

[marcosdumay]

If I had to guess, I'd say that single-machine (with cold backups) is the most common way to use Postgres with a web server.