To your main point, all general purpose languages are good enough at everything. That's how they get to be called "general purpose". But, I would argue that there are 0 languages that are great for everything. There is no language that can be shown to have 0 tradoffs when compared to all other languages.
The thing that often gets over-looked with Ruby is the trade off that many other languages make of developer time and enthusiasm (happiness, comfort, engagement, morale, etc). If you don't believe those factors exist or that they have little value then the trade off the language makes to afford those features is lost in translation.
To make a crude analogy: if I were hiring to get a company off the ground I would love to find a single person to do all of the product concepts, design, implementation, sales, accounting, legal work and support. The problem is that the jack of all trades is master of none and you're likely to get some creative concepting all over your accounting. Languages specialize in thousands of ways over the growth of the language (and hopefully consciously) - much like people do with education and career development. Even at times under the guise of general purposeness.
This is all to say that unfortunately your wanting a language that is great for everything is impossible. But, you might find a language that is good enough at all of the trade-offs you care about without ever trading off all the other things you care about and for all projects for all time.