And to be fair, those are all great general purpose solutions. For example, you could also use Postgres or Redis as queue, instead of say Redpanda or Kafka.

But our customers need separation of concerns in their architecture. While they could put the cash in the general purpose filing cabinet, they actually want the separation of concerns between OLGP system of reference (string database, i.e. PG) in the control plane, and OLTP system of record (integer/counting database, i.e. TB) in the data plane.