On this line of development a customer of mine has a lot of small/medium Rails applications with very little in models and controllers and almost all of it in service and command classes. They use commands for code that does only one big complicated thing and services for bags of simple methods about one resource.

They end up with code like

  class Command
    def initialize(a)
      @a = a
    end
    def run
      s = Service.new(@a)
      s.do_something
      s.do_something_else
    end
  end
  Command.new("a").run

which is funny when I think that in Elixir I would write Command.run("a") and there isn't a good reason for using OO in this case, except that Ruby is very object oriented. Anyway, their code is quite separated from Rails except for the calls to ActiveRecord, but that could be ActiveRecord without Rails.