When I see Lua, the only thing I ever read is "great for embedding", "fast", "lightweight" and more often than anything else: "World of Warcraft" or in short "WoW".
Why is it limited to embedding the whole thing into another application? Why not write general-purpose scripts like you do with Python or Perl?
Lua seems to be doing great in aspects like speed and memory-usage (The fastest scripting language afaik) so why is it that I never see Lua being used as a "Desktop scripting-language" to automate tasks? For example:

Renaming a bunch of files
Download some files from the web
Webscraping

Is it the lack of the standard library?
I think the answer about it being a "marketing" thing is probably correct, along with the lack of a large set of libraries to choose from. I would like to point out another case of this: Ruby.  Ruby is meant to be a general purpose scripting language. The problem is that since Ruby on Rails has risen to be so popular, it is becoming hard to find something that is unrelated to Rails.  I'm afraid Lua will suffer this as well, being popular because of a few major things using it, but never able to break free of that stigma.
Lua as a general-purpose scripting language?