I think what happens with Lua (which does, incidentally, have many solid ecosystems built with it) is that it just gets quietly used in industrial-strength ways

I think what happens with Lua (which does, incidentally, have many solid ecosystems built with it) is that it just gets quietly used in industrial-strength ways which don't require too much fanfare/promotion in order to propagate it as a tool - which is not the case with node, which aims to be a solution to industry-wide problems which Lua solves in other ways. One thing that I think people get confused about Lua is that its simultaneously a VM, a language, and a very minimal framework, around which many, many things can be glommed. The glomming of those things is so flexible and versatile that - indeed perhaps we see too much diversity in the Lua appliance world, for there to be any common centralized traction around promoting it, as has happened with node. If you want to see how Lua really has a solid ecosystem, then you have to look for projects that have embedded the VM and are using it as the basis for their application run loop. And indeed, there are plenty of projects out there doing this, that it can't really be said Lua doesn't have traction; it just doesn't attract as much hype. Lua has plenty of libraries; its just that the "FFI all the things!" approach means that you can, pretty much, indeed FFI all the things. No standards committee required!