I replied directly to you sighting the specific reasons this is non-performant in an RDBMS, and you simply ignored it. There is also nothing to disbelieve abou

I replied directly to you sighting the specific reasons this is non-performant in an RDBMS, and you simply ignored it. There is also nothing to disbelieve about the system described in the parent comment. It a perfectly sound design pattern. It’s just not an RDBMS. It is a system that uses an RDBMS as an object store, and then uses external systems for enforcing ref and check constraints, schema definition, querying, mutation and consistency. If you’re just using collection of RDBMS to store objects, and performing all other operations in external systems, then RDBMS design constraints are mostly irrelevant.