All this does is make writing a CHECK constraint for a JSON blob relatively straightforward. And yes you should use CHECKs in the database. In practice, it is very easy for application code to either not check or screw it up. It is much harder to find and clean up bad data in the database than prevent it from being inserted. By making it a schema config, it is much easier to audit by other engineers and more likely to be correct.

If CHECKs are causing perf issues, then okay maybe put the problematic ones somewhere else.