usage for 'with recursive'?

there have been a discussions about how posdtgresql needs 'with
recursive' queries.

not that i would like to object the idea (new feature is always a
good thing), but is anybody able to show me real usage of this kind of
queries?
as i see it the only usage for 'with recursive' is when one have a
tree-structure stored as:
create table objects (id serial primary key, parent_id int references
objects (id), ...)
and one want to do some "deep queries" without client-side recursion/loops.

is it the only thing 'with recursive' is useful for? i mean it sounds
unrealistic given that better data-structures for tree hierarchies
have been proposed and implemented.

best regards,

depesz

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