> The data you get out of the database will be untyped.

Uh, no. Nearly all database access protocols maintain type information for the resultsets returned to the client. That's definitely the case for postgres (cf. RowDescription in https://www.postgresql.org/docs/devel/static/protocol-messag... , accessible to the provided client library via PQftype,cf. https://www.postgresql.org/docs/devel/static/libpq-exec.html... )

There's plenty cases to be made against RDBMs. No need to invent more.