Because I said so.
Just kidding.
I see what you mean, but I think that context disambiguates the meaning/misuse of "literally" only in the sense that it reveals the misuse. When I hear someone say, for example, "I literally slept until noon," after I've rolled the sentence around in my head and concluded that there's no reason why it wouldn't be taken literally, I then understand that it's being misused and that what the person means is
actually, not
literally. So I mean, it's just a big mess. It
causes ambiguity and confusion. And when someone actually does mean something literally (correct usage), he may very well be misunderstood as meaning actually or figuratively, because the real meaning of literally has been buried (or, I suspect, never known in the first place by a lot of people). It's a bit of a boy-who-cried-wolf type of situation. It creates confusion. Language shouldn't be confusing.
As a matter of fact, I recall reading that the modern epidemic misuse of "literally" can be traced to the Kardashian girls (from their television show). It's like this: after World War I, a guy called Edward Bernays (he was Freud's nephew, actually) hired a number of fashionable young women to smoke cigarettes while marching in a televised Easter parade in New York City. (Up to that point, cigarettes were viewed as phallic symbols,--i.e. symbols of male power,--so it was regarded as gross and wrong for women to smoke them because, you know, men didn't want women getting any ideas about power and freedom and such.) The next day, cigarette sales exploded. Women started smoking like crazy. Likewise, when Kim Kardashian says, "I like, toooootally like, literally can't even like, remember what I was about to literally like, kind of say, you know, riiiiiight?" then a large number of people think: "Kim Kardashian is famous --> she's fashionable and a sex symbol --> I want to be famous, fashionable, and a sex symbol --> I'm going to speak the way she speaks." (Actually they don't
consciously think that--it happens in the unconscious mind... Freud again.) So they
do start speaking like her...and the people who don't care about Kim Kardashian hear the Kardashian clones saying "literally" incorrectly, not knowing that it originated from Kim's misuse, and their unconscious minds say: "Everyone's saying 'literally' all the time now --> They're misusing it --> But I want to fit in --> I'm going to say 'literally' all the time now, too."
[I had to edit this, because the top part didn't make sense in some places. Sorry...I'm only halfway through my cup of coffee this morning...]