Why does a Postgres recursive CTE need the list of columns as argument?

This is kind of a subjective question.

If I have a recursive CTE something like:

WITH RECURSIVE r(x, y) AS ( ...    SELECT x, y -- select1    FROM t WHERE ..     UNION    SELECT t.x, t.y -- select2    FROM r JOIN t    ON ...)SELECT x, yFROM r

What exactly is the point of specifying the list of columns as an argument in the CTE definition? If I don't specify it, it anyways takes the list of columns in the SELECT.

If I do specify it, every time I want to make changes, I have to reflect that in both the SELECTs in the CTE and also in the argument list.

What benefit do I gain from writing WITH RECURSIVE r(x, y) AS instead of just WITH RECURSIVE r AS?