There is a strong culture of dog-fooding in Amazon. The advantages to it are quite straight forward :) If you've got a whole bunch of DBA experts already hire

There is a strong culture of dog-fooding in Amazon. The advantages to it are quite straight forward :) If you've got a whole bunch of DBA experts already hired, why would you hire additional people to do DBA work for every team, when they could just use RDS? Along with that is the huge added benefit of a direct feedback loop, with consumers and producers able to directly meet and deal with feature requests, problems etc. etc. Retiring any of the services that have been launched would cause not inconsiderable pain to other teams :)