I am very much in camp “minimize your dependencies and take the utmost advantage of what you already have” but I also am in camp “your database is the most important bottleneck component.”

This has two implications:

1) make sure if you use Postgres for anything beyond core rdbms functionality that there is no dependency between the two, so you can rip out the additional functionality and move to a different platform when you end up needing to reduce the load on your db server

2) if using Postgres for non-essentials complicates your db backup workflow, risks the data integrity, makes it difficult to maintain or upgrade your Postgres instance (eg you have to wait months or years for compatibility with newer Postgres versions), or loads relatively shoddy or unstable code into the beating heart of your application, then you should either use a different Postgres server/install/container for these ancillary services or bite the bullet and introduce an alternative dependency, depending on which makes more sense.