Telling kids NO leads to failure

My cousin came over about 2 years ago, said she need time away from her husband. Ok no big deal. I told her son no he couldn’t have some snack he said “ my momma said can’t no one tell me no I can have what ever I want” so I asked her about this she said she don’t tel her kids no because she don’t want them to think they can’t do something or they can’t have something. I’m like they will hear NO through out life she says if i tell them no they will grow up believing they can’t accomplish things and be failures. I’m like well In this house they will hear no because kids can not have anything they like. She was so offended and said thats why she left her husband because he was telling the kids no. I tell my kids no. She says kids should be able to learn that what they doing is wrong on they own and not be told no. I’m not judging her parenting style but I do feel kids need to be told no at one time or another. She then said she let her kids make they own choices and rules. Her kids are 1, and 5. Does anyone else not tell they kids no?