Those Americans on list have a right to question their accuser in court before a right (to travel) is restricted. When did we agree to suspend due process, 14th amendment?
Or, to put it another way, governments can make people disappear by publishing such lists and having the police be busy somewhere else when a mob happens.
Don’t be so naive. Lists of people are almost inherently dangerous things. I don’t like that a no-fly list exists in the first place but it would be completely irresponsible to just publish it and wash your hands of it.
How would they know? How would they prove it?
There's a known case a few years ago where a woman was trapped away from the US for 3 years - her estranged husband put her on the list when she went to visit her parents, and boom, she's not allowed into the US and no-one will tell her why, making it easy for him to get divorced and keep the house.
(If she'd known what had happened, and been able to put her hands on enough money, she could maybe have flown to Canada/Mexico and entered overland; all she knew was she was denied boarding)