I've read about places that do this kind of stuff. Although it sounds like pure hell, I'm sure there's always a reasonable explanation, an intent. What kinds of problems was the org facing that led to the development of this?
It wasn't really necessary.
It also made the core superapp a blocker of essentially every user delivery.
If it has to do everything, then you have to add a lot of features to it.
So you have N devs doing jinja/yaml/dsl and N/4 doing core superapp underlying dev.
For the first Z features/projects, you inevitably see new things that your superapp doesn't support yet, and becomes emergent blockers midway through implementation.
Given the ratio of devs, new blockers were being generated faster than they could be cleared.
Eventually business side pulled the fire alarm and grabbed most of the devs over to use a more common AWS-centric service directly and exit the superapp dev use completely.
IE - if you are going to depend on something, would you rather it be an AWS service with 10s-100s of dev-years behind it, or some internal superapp spun up 3 months ago with 2 guys on it? Which is more likely to already support what you need?