I give a list because I spend a LOT of time checking the parentage for rust resistance of the cultivars they sell. More daylilies than not show susceptibility. I've given Maryotts a list with both orders and get any bonuses from that list. I don't want rust buckets in my garden. I am ridding myself of those cultivars. So I prefer to be specific. And my bonus list is usually inexpensive cultivars. Cheaper plants than what I bought. I have done that with two other sellers too. They were happy to oblige and I was happy getting plants that I felt would survive in my yard.
Oddly, I've never asked for any of their intros because of parentage. I don't use chemicals to control rust, so I really have to be specific. I sure wish I didn't have to deal with the rust issue because there are so many gorgeous cultivars I wish would do well here, but I know the limitation of living in the south with high humidity. So I guess I am one who doesn't prefer surprises.