Saying Warnings are meaningless because they can be ignored would literally flip the entire legal system on its head. That is literally an insane way to think about things.
Not all warnings are equal. Are you a negligence or products liability attorney? You think that a warning that is easily ignored and moved past to do the same thing anyway is sufficient to obviate liability? I don't think the law agrees with you there. Not sure what you think is so insane about that.