[L0stLink]

It is extremely difficult to design a good RDBMS schema without understanding the data model, and once you do, it is there documented in its entirety with best in class tooling for anyone else to come along, pickup and be up to speed with it, additionally you don't have to forgo document storage, most if not all modern RDBMS suppord json(b) types.

[lmm]

RDBMS tooling is a long way away from best-in-class, and the data model is extremely awkward in a way that actually distorts your modelling (no collection columns, no sum types...) and there's no real support for keeping track of schema evolution. I agree that recording your schema model explicitly and keeping track of it is very important (using something like Avro's schema registry), but RDBMS tools are not actually that great at it and using an RDBMS brings in a lot of other baggage.