What if the limits on the lateral subqueries were 2 instead of 1, and they were doing select * instead on select sum() in the outer query? How would you recreate that with correlated SCALAR subqueries? There's no such thing as non-scalar correlated subqueries is there?
SELECT unnest(ar).* FROM
(SELECT ARRAY(SELECT tbl FROM tbl
WHERE .. ORDER BY .. LIMIT 2) AS ar
FROM .. OFFSET 0) ss;
If you want a specific set of columns instead of *, you'd need to create a custom composite type to create an array of, since it's not possible to "unpack" anonymous records.
