[ary]

When S3 was released the Internet was very different. Two of the things that stood out were:

1. It offered a resilient key/object store over HTTP.

2. By the standards of the day for bandwidth and storage it was (and to a certain extent still is) very inexpensive.

Since then much of AWS has been built on the foundation of S3 and so its importance has changed from merely being a tool to basically a pervasive dependency of the AWS stack. Also, it very much is designed for objects larger than 1KB and for applications that need durable storage of many, many large objects.

The key benefit, at least according to AWS marketing, is that you don't have to host it yourself.