I think the thing missing here is that the killer domain isn't necessarily intrinsic to the language or its design. Some languages are designed for specific dom

I think the thing missing here is that the killer domain isn't necessarily intrinsic to the language or its design. Some languages are designed for specific domains, but some find their domain based on large projects that happened after the language was out in the world. My understanding is rails came almost a decade after Ruby, numpy etc came well after python. This post says that you shouldn't try to use a language outside of its domain, but if everyone believed that, languages would never find a new domain.