The leaves of the daylily need to be allowed to die back to brown on their own in order to
feed the bulb.
However….
I used to cut about half of the leaves from the plant after flowering – so that the remaining plant looked a bit like a ‘fan’. I did this so that I could tidy the area up a bit and get a good look at other plants that were growing in between them.
This didn’t produce a lot of mulch – but it did produce some.
I like the idea that the daylily serves multiple purposes: Food for people, birds, pollinating insects, beauty, and some mulch. And, in the right growing conditions they multiply fairly rapidly giving you a perennial resource. They can also be potted up and sold or traded.
I say tuck a daylily in every nook and cranny
-- Oh yeah, and I never watered mine. Another plus.