So what? Does that invalidate them somehow (other than in your mind)?
They may even offer reasonable rules for living, but they don't provide purpose.
Again, all you are saying is that you disagree with them. So what? What makes you think that is a useful point here?
No it doesn't invalidate them, the rules are not necessarily wrong or false. It's just incomplete. It just doesn't offer purpose for our being here. It's no more invalid or false that Amy Vanderbilt's guide to etiquette, but it doesn't answer the big questions of"why are we here?", "what is our purpose?, "is there life after death?", "if so then what?"
Religions that are nothing more than lifestyle rules don't even attempt to answer those questions. The Eastern Religions do but do so in a way that I find them irrelevant.