It all depends on what, if anything, is the function of the pigment in the leaves the appears under certain conditions and in certain plants.
We might look at what researchers think is the function of pigment in autumn leaves of some plants, and of pigment in spring leaves of other plants and compare that with what we might think is similar in daylilies.
Then the question would be whether anyone has objective evidence that there are differences between daylilies with the pigmented leaves and those without pigment in their leaves under the same conditions. That would be quite difficult to show since there can be so many other differences between any two daylilies. The first step might be to find a cross that produced some seedlings with the pigment and some seedlings without the pigment and compare them. I would be surprised if anyone has done that. I would be even more surprised if they measured characteristics carefully to compare them.
