Postgres, a relational database management system, was chosen over a message queue like Kafka for Dagster Cloud's logging system due to its familiarity and performance. Despite initial concerns about using a relational database as a message queue, Postgres proved suitable with proper configuration, such as archiving and rate limiting, which helped scale the database and mitigate issues like unbounded growth and spikes in customer log volume. The decision was also influenced by the philosophy of choosing the right tool for the job, rather than relying on new infrastructure, and minimizing additional costs associated with learning a new technology. While Postgres has its limitations, such as not supporting multiple regions or requiring downtime during failovers, the author acknowledges that these issues can be addressed in future work.