It's a janitorial service of sorts, and it's totally appropriate for some corps to contract it out. It allows the developers with the best knowledge of the business to focus on that, where value is created. Regressions are mitigated by a strong culture of testing.
Managed properly, rails and ecosystem churn is manageable. Managed poorly, it becomes reasonable to bring in an expert to repair your neglect.
But it's definitely true that rails culture doesn't make itself easy to manage.
Also, I have yet to meet a team that has all the developers it wants, with all the expertise they desire. Maybe FB and Google, most other places need to focus their talent on what will bring best value.
It actually makes more sense on bigger codebases then on smaller.
Most people unfortunatelly are stuck with old codebases and will have to wait before they can use something shiny like this in daily work.
Last few years, majority of my work in Rails is upgrading older apps to current, for security mostly.
Really great update, congrats DHH and the team.