If you are referring to my post, it's about web applications. I'm not in any way claiming that postgres is a crud app. I'm describing how to design a good web application that mostly revolves around a database. Which is what people mean when they say crud app. It's just any app that's mostly crud. Where the majority of the logic can be handled by the database like I described.

A lot of apps are just about putting data into a DB and then providing access to that data. Maybe using the data to draw some nice graphs and stuff. That's a crud app.