That really points out how much of most commercial or governmental websites have dependencies they don’t recognize. Which dependencies have further dependencies they not only don’t recognize, but can’t recognize.
It’s a very, very deep and very tangled stack of unknown unknowns.
This is illustrative, even though it’s about units of software, not groups of servers:
from xkcd: Dependency
You don’t have to pull out a very large slice of the total before the whole thing (or sections of the whole thing) come tumbling down.