SQL does express relational algebra, but OP is arguing it expresses it poorly, in a cumbersome way. There's nothing foundational about how exactly SQL chooses t

SQL does express relational algebra, but OP is arguing it expresses it poorly, in a cumbersome way. There's nothing foundational about how exactly SQL chooses to express relational algebra, you could imagine many different syntaxes and specific semantics. I concur, SQL is a liability in many ways.