That Moment Changed Everything: What's the Catch With S3's "11 Nines" Durability Claim?

https://blogfreely.net/weyladikle/why-amazon-s3-compliance-controls-matter-for-storing-financial-data

Which questions about S3 durability will I answer and why do they matter? When Amazon S3 advertises "11 nines" durability - 99.999999999% - it sounds like an absolute safety net