At least with the 2008 manual I looked through, the warning (which doesn't seem to be as detailed as the more recent one) appears in section 5-2 of the manual. Well past all the dire warnings about using seat belts and how the car may contain chemicals known to the State of California to cause cancer. I wouldn't conclude--based solely on this evidence--that everyone would be fully aware of the seriousness of letting the car discharge fully.
Of course, Tesla may emphasize the point in other ways.
That's the general problem with the omnipresent safety warnings you get with products. The important and possibly non-obvious get drowned out by the all the boilerplate silliness.
You really can't fault Tesla for putting the battery warnings after the legally required warnings. They most likely have no choice. Now, if the battery warnings aren't immediately after the legally mandated warnings, that is Tesla's fault, but you have to keep in mind that it is totally reasonable to expect a first-time EV owner to read the section on charging.
Of course, Tesla may emphasize the point in other ways.
That's the general problem with the omnipresent safety warnings you get with products. The important and possibly non-obvious get drowned out by the all the boilerplate silliness.