So, in a declarative system those things also exist, but they are written once (by the framework developer), instead of x1000 by each user. Its like a SQL join

So, in a declarative system those things also exist, but they are written once (by the framework developer), instead of x1000 by each user. Its like a SQL join- I can declare a SQL join in SQL and let the RDBMS figure out the code(in which case I would need to verify the impl only once as part of the DBMS). Or I can offer NoSQL, and do a join in code by each user. I prefer to former. When you want everything as code, you basically LOWER the level of abstraction. All the tools that you mentioned, can also be run in a declarative system, but they need to run only once (by the framework/RDBMS) , instead of by users.