The question
You're five to fifty people, pre-Series B. You've picked the tools — one cloud account, one payment processor, maybe one identity provider — because picking one of everything is how a small team moves fast. Nobody has mapped what actually depends on each one, because nobody has time to draw architecture diagrams for a company this size.
Then a fundraising round, a board meeting, or a new hire who asks "what happens if Stripe goes down" makes you realize you don't actually know.