Atlas vs. Heroku and other PaaS
PaaS, like Heroku, typically manage the entire application and service stack within their own infrastructure. This means creating services on a PaaS is very low effort.
However, as infrastructure grows in complexity, a PaaS may become too opinionated to handle new business requirements. At this stage, you must either bend your application to fit with a PaaS or move off of it.
Atlas attempts to bridge this gap and is focused on the workflow of deployment and infrastructure management, rather than where applications run. For example, Terraform can manage Heroku resources and combine them with AWS compute.
Depending on the legacy requirements, cost structures, and service availability, a PaaS may be too simple for some applications. In this case, Atlas can bring a similar developer experience to lower-level service and infrastructure providers.
Atlas is built on the open source HashiCorp toolset, so configurations can be taken out of Atlas and still function in different environments. In this way, Atlas avoids lock-in, typically a problem with PaaS providers.