That is true. But there is more richness to tables/relations with their set-theoretic operations. What are the operations you can perform on a LIST? Well maybe

That is true. But there is more richness to tables/relations with their set-theoretic operations. What are the operations you can perform on a LIST? Well maybe the LISP like operations CAR CDR etc. But those are not very good set of DATABASE operations, like SELECT etc. So relational means every operation produces a result to which all the same great set-theoretic database-operations are applicable. That is why it is a great basis for databases.