Because the process of building that SQL, executing it, and bringing the data it returns into the object oriented universe is a tedious and fiddly pain in the arse.
1. “Building SQL”? It’s not clear to me what that means in a world where you are writing raw SQL rather than using ORM’s and query builders.
2. “Executing it”—this is called a SQL client library. If you install your SQL statements as stored procedures you can execute those procedures by name, for example. Not that hard.
3. “Bringing the data it returns into the object oriented universe”: I am typically satisfied with an array of hash tables. Funny story: what do you get when you use ActiveRecord’s find_by_sql with a query that returns columns not in the original table? You get a collection of objects each with the extra column monkey-patched to the individual object. In other words, a slower and stupider hash table that happens to have dot syntax rather than bracket syntax and a bunch of do-they-even-still-work-in-this-context instance methods attached.
