After having tried searching for "linothorax" or "cloth armor" I retrieved only results for the pocket brigantine (cloth with leather pieces sewn into it).
Therefore, (and I do apologize if my search was not thorough enough) since the linothorax was historical and effective, why is it not allowed as valid Belegarth armor? It seems odd to me that unhardened leather may be used if it is 3/16" thick and would realistically provide no protection whatsoever, but the hardened/layered cloth may not.
Yes, I realize we play a sport that is not real combat, but the option seems, to me, a valid one to have.
I respectfully await your answers.
***EDIT*** in response to answers:
Thank you for your timely responses. Those reasons given are entirely understandable, and they do have merit. Your suggestion of trying it out in my own realm seems to be the best solution, and that is probably what I will end up doing. And for clarification to the second replier, the linothorax is glued layers of cloth, so it ends up being just as rigid and encumbering (through immobility/inflexibility and body heating due to it becoming a non-breathing material rather than by weight) as hardened leather armor. Wikipedia has an informative article on it, but I digress. Again, I appreciate your insight, Happy New Year!