Not everyone is working on a startup trying to peddle their stuff to a zillion users and getting hammered in the process. If you ever get to Twitter/Facebook/whatever size no out-of-box solution is going to work. You'll end up doing what Twitter did which is re-architect all their infrastructure/code and tune all their stuff as much has possible.
Ruby's issue IMHO is that it has always been a Rails-centric community/ecosystem and never had the change to grow beyond that. It's still largely used to write web stuff and nothing else. Python, which is a "similar" language, has a much healthier and more diverse ecosystem being used in things like scientific computing or computer vision.
If you want to make Ruby better, grow beyond the web application ecosystem and make it more diverse.