[mmanfrin]

  Making Ruby/Rails maintainable at scale is a sisyphean task: 
  it's possible, but at an enormous cost

Disagree. I've worked at two companies now with teams of less than 6 maintaining rails apps that have handled billions in sales.

Rails can scale; the problem that Rails faces is that it is easy to get things going quickly, and lack of foresight or simple inexperience can create bombs of technical debt or scaling issues. For many years, Ruby was the lingua franca of 12-week bootcamp schools, and the code that that cohort of programmers made spanned the spectrum of quality, but it all went to production.

In other words, the problem with scaling Rails is not with the framework or with Ruby, but with the accessibility and ease of development making it easy for pernicious problems to enter the foundation of codebases.

Good ruby scales, bad ruby does not -- both exist.

[blasdel]

Another major pain point was the constant dependency churn in the RubyGem ecosystem, but all of that noise seems to have moved on to NPM along with the hype and bootcamp curriculums.