[skrtskrt]

My experience is along the following lines (same for Django as well actually):

1. Company started as Rails monolith

2. Some components of the Rails monolith stretch Ruby capabilities beyond where "throw more servers at it" is still reasonable or effective

3. Factor out some backend functionality into dedicated services which can be scaled separately, Rails still serves as the API gateway calling these services. Anything without scaling issues stays in the monolith for now.

4. Eventually Rails is just an API gateway, no one in the org knows Ruby/Rails and its dependency management madness any more, and it gets replaced with a more-performant, purpose-built API gateway, usually something off-the-shelf.