You don't build projects with your pets.
Discussions that are prolonged like that become long because people are not actually being _objective enough_.
If you had an objective discussion about Python and Ruby you would conclude that yes, both of these languages have very broad ecosystems and are particularly suited for scripting (and glue work). Python is better suited for scientific computing, etc.
Nothing about the scenario you speculate about invalidates good discussion about programming languages and I don't know what about the scenario makes you think it does.
I agree - nothing invalidates good discussion on this topic. My point is that trying to decide the best programming language for a particular task (or trying to decide why one programming language is ill-suited) isn't something that always needs a perfectly objective answer.
Ok, I hear that. I agree that you have to find a local maximum to settle at in these things. It's about being reasonable and pragmatic, after all.
Sometimes using a band saw to conduct brain surgery is just completely wrong.
It's pretty clear that COBOL would be a bad choice to write a multiplayer online game, and that JavaScript would be a bad choice for an operating system.
As for the far far more common scenario (the one I had in mind) of choosing whether one of Ruby, Python or Node.js might be better for a certain project, the choice between the three is often going to be fairly subjective. You could solve a lot of problems in all three quite well. Trying to decide which one is objectively the "best" is often a waste of time that could be spent actually solving the problem at hand.