ignaloidas parent
It's because S3 api is quite a fair bit worse than what they offer. They define their guarantees for storage products way more clearly than other clouds, and for blob storage, from my understanding, their model is better than S3.
https://en.wikipedia.org/wiki/Worse_is_better
The alternative take is that trying to have a party on your remote island is objectively a bad party because no one else will come