there were a few reasons behind this.
- ease of migration was a big one, we had 100+ instances of bitly's oauth2_proxy, and were able to seamlessly migrate them to this, without any changes to the services being protected.
- ease of deployment was also important. Our solution doesn't have any datastore dependencies, and is stateless, so was straightforward to deploy into our PaaS ( https://tech.buzzfeed.com/deploy-with-haste-the-story-of-rig... ).
- when we built this, there were far fewer solutions than there are today. For example, Ory's Oathkeeper ( https://github.com/ory/oathkeeper) was released after we were already using sso internally at BuzzFeed.
thanks!