I personally DO use Lua sometimes to code general purpose stuff.
Still, I don't see Lua ever having "batteries", the language wasn't invented for that purpose, and the original sponsor of the language wouldn't want it changing in that direction (I dunno if they still sponsor it though).
Lua was invented by PUC-Rio (Catholic University, Rio de Janeiro campus) at the request of PETROBRAS, its purpose was "describe" stuff, and replace another language that they already had, plus being turing complete, because they got tired of hacking things endlessy whenever they needed to describe something "new" in their systems.
So to "describe" stuff, Lua doesn't need libraries.
That said... currently Lua most popular use is add some kind of scripting environment to other software, still that often means a library would be useless, and even then sometimes that usage is still to describe things, for example the game "Crusader Kings 2", use Lua to read a file named "defines.lua", and all it does is set some constants, another use of Lua that I find interesting is "xmake", Lua programs in it are very descriptive, using Lua syntax features to "tell" things to the system, instead of looking like anything resembling a normal imperative program.
EDIT: about community size... yeah, it is tiny :( I never found a Lua job, companies that use Lua often hire a programmer of other languages and teach him Lua, I am also currently using PUC-Rio official GUI library (iup) and never found anyone else using it to ask questions about it, I've been in PUC-Rio during a tech event, and when I asked around if anyone knew where Lua authors were, the people that study and work there, didn't knew they had anything to do with Lua in first place!!!