Ruby is unsuitable for large projects for the same reason python is, but it also lacks the huge ecosystem and labor pool that python has. When I'm interviewing and a company tells me ruby is the main language, I end the call.
(Which is not to say X is flawless even at scale or a clear best fit along all axes. That is true for no X that I know of.)
That hasn’t stopped billions of dollars of revenue from being created with it.
At least Ruby is unpopular enough (compared to Node) that people who know it are probably decent at their job.