I may be reading a bit extra, but my main take on this is: "in your app, you probably already have PostgreSQL. You don't need to set up an extra piece of infrastructure to cover your extra use case, just reuse the tool you already have"

It's very common to start adding more and more infra for use cases that, while technically can be better cover with new stuff, it can be served by already existing infrastructure, at least until you have proof that you need to grow it.