This is exactly how tightly coupled, unmaintainable software is constructed.

By picking the tools before understanding the model and building bespoke architecture.

You pick the tools that the business model requires. It might be a relational data store. It might not be. You might want an event store. You might want to reduce costs with lambdas and DynamoDB. You may need a pub/sub event broker.

The OP clearly loves Postgres. Cool. They also have limited experience with complex systems architectures because if they had that experience, they would have never written this article.