Disagree on that one, honestly. I've found the real cairns are usually placed right where you NEED them, like above treeline when the fog rolls in. People build their own little rock piles for fun or photos and THAT'S what causes the confusion. The official trail crews know the sight lines. Following the random stacks is how you end up off trail.
Saw a park ranger interview about this once. They said the fake cairns are a huge problem out west, like in Joshua Tree. People build them for fun near the actual trail markers. Then when a dust storm hits, hikers follow the wrong line of rocks and get lost. The real ones are placed by pros who know the land. It's wild how a little rock pile can mess things up so bad.