For me it was a sequence of books that did it. The Phoenix Project first, then David Anderson's Kanban book. Some tine after that was The Goal and Deming's Out Of The Crisis, and a book of Taichi Ohno musings.
You're right, what has been seen cannot be unseen.
It's interesting for a number of reasons, not least because it explains that a lot of the ideas driving how Toyota worked post-war came from the fact that they knew they wouldn't be able to let people go in an economic downturn.
You're right, what has been seen cannot be unseen.