[dgb23]

The schema restrictions you can express in SQL are both insufficient and not flexible enough even for relatively trivial things, except you are either fine with storing and retrieving things in a completely different shape than you actually need, or if you are fine with constantly migrating your schema.

That's not a sufficient argument against adopting SQL for something, but other solutions are certainly _not_ just SQL with extra steps. Not everything maps nicely onto flat tables with predefined slots.