At the scale $EMPLOYER works at, AWS built in services are key. Things like DynamoDB global tables are extremely hard to run on your own, and things similar to AuroraDB and Kinesis can be run on your own but they take up a lot of personnel hours better spent focusing on product. We could probably eliminate those services and self-run, but it would be an extremely unwise usage of company time and money.

But we also run services in multiple continents with the need to handle clients doing silly things like getting into airplanes and flying into another continent. Your situation might not benefit as much from AWS specific services, so YMMV.