The first two linked resources:
Simplify: move code into database functions
Just Use Postgres for Everything
Are disqualifying enough to not warrant further reading.A relational database is one form of persistent storage. They are great for managing persistent representations of key abstractions and their relationships.
They are not application frameworks nor scalable messaging systems by design.
Not everything needs to “scale.” I think needing scale is relatively rare, actually.
Did you see that implementation of Quake in CSS? Or Tetris in awk? You can do a similar thing with Postgres, and it will be much less insane. Should you run your entire app stack in Postgres? Likely not. Can you? Likely you can.