Hello friend @gamesorry . Maybe I know the reason why this rule is in place. There was a certain user (whom I will not name) who was very keen on hijacking entire threads with dozens of posts at a time (and also very prone to deny it, in-your-face evidence notwithstanding). Fortunately, that user has since been banned from the forums, but I can only assume that they put this kind of fail safe just in case.
Anyway, sorry for not giving much support to the cause, but at least I’ll make sure to hover around your thread and make sure to post a placeholder response to avoid this kind of limitation.