Why do people say some lego sets are hard?

This is a genuine question and I don’t mean anything in an offensive or negative manner. I have personally tried a couple sets that are considered “difficult” by people in the lego community and didn’t find any of them particularly taxing. I thought lego’s inherent purpose was following instructions and you’re good to go. Like sure, maybe you can mess up and have to restart, a particular piece is difficult to insert in a technic, or a project might take a long time. But I honestly feel like...