In writing for beginners the author should just say something truthy like: "A relational database is a database where all data is stored in values of an algebraic data type called a 'relation'. SQL uses the word 'table' instead of 'relation', but the two words mean roughly the same thing."
What you've written here is worse, for the simple reason it is now semantically wrong instead of just syntactically wrong in the use of the word relational.
As an example, all relational databases that the average reader can be expected to have heard of use bags(multisets) instead of sets, so they in fact don't store data in relations.
Language gets polluted over time. Trying to force a technically correct but obsolete meaning is not helpful to anyone.
What you've written here is worse, for the simple reason it is now semantically wrong instead of just syntactically wrong in the use of the word relational.
As an example, all relational databases that the average reader can be expected to have heard of use bags(multisets) instead of sets, so they in fact don't store data in relations.
Language gets polluted over time. Trying to force a technically correct but obsolete meaning is not helpful to anyone.