Comment by toledocavani

Worked in an enterprise project where they use a BPMN engine for all business logic (designed by non-technical people).

Each process can either have predefined fields (take time to implement) or key-string value store (yes, they chose this).

Either the BPMN logic or some JSs (some, as not all people can code) in PBMN nodes or some Java hooks (a lot, wrote under those other people requests) edit those values.

So when something's wrong, we swam in the sea of key-value, search all the code for who update this field, and why it's value is not JSON nor null nor boolean but a string "Not used, waiting for policy 1234".

After that project, I'm happy every time I can use a DB to store data, more so if it can run in local, much more so if it's relational.