In some cases, understanding when you are or are not may only be important for understanding your own scope and responsibility. Knowing that you are not responsible for data loss when someone in management above you refuses recommended backups is important for sleeping at night or telling a future employer about a previous role.
Knowing that you do (or do not) actually run IT could be potentially important for explaining in a court case who is responsible for decisions leading to breaches, data losses or violations. Titles do not matter in court, roles do.
But in a more day to day, practical sense, explaining to management "above you" at your job that they have decided to take over as the head of IT and that that impacts how you and they need to think about your job. Maybe this can make your job better, maybe this can help management understand business failings. But if we can't put these things into words, we cannot begin to address them.