Why I need to use SETOF TEXT when I'm returning single column?

If I'll make my functions like this:

create function test( out a text, out b text) returns setof record ...

it works well.
but if i have just one column in returned recordset, I cannot:
create function test( out a text ) returns setof record ...
shows:
ERROR: function result type must be text because of OUT parameters

it's bad because I can't have the column names the way I want it to be
named! (well, I could, using custom datatype, but it's besides the
point.

is there any particular reason why returning single-column "setof
record" is not allowed?

Best regards,

depesz

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