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 mach

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.