Sure, it WOULD be possible to write something grammatically correct without any commas at all. It'd be exhausting to read, though, and you wouldn't be having a lot of syntactical variety in your language. I don't really understand the purpose of this poll since I can't see why anyone would find commas entirely useless.

grammar * or interpunction. Sorry. I meant to say interpunction. LOL

Not just useful, but VITAL. If you can't use proper grammar I suggest not to write fan fictions to begin with. Just saying.