Right... and if we use the "modern sloppy" definitions of "literal" and "decimate" -- sigh.
This is why I always argue for precision in writing. If someone writes that in a history book or a text of some sort, how will it be understood, and how will it be relied upon as an "accurate account" if the words are plastic?
Well, as Yudan said, I think that the use of "literally" as a form of emphasis or exaggeration would not be used in history books since it seems to be a more casual way of speaking. I don't think it hinders communication when it is used in a conversation; when I hear someone say "she literally tore his head off!" it's pretty obvious to me what he's trying to get across, whereas I would be surprised it I read that in a history book.
Also, I'm not sure if this is what rich was saying or not, but when I see "decimated" I do not think "1 men in 10 executed", I think "annihalated" or something along those lines. I would guess that most people would think the same way - the most literal and precise definition of that word is actually the more confusing one, if it is used in a sentence that way. The clearest way for a writer to say that would probably be to just spell out "1 in 10 was killed". I think perhaps it is necessary that a language be flexible and adaptive, as long as people can still communicate clearly.
Not trying to be argumentative or anything by the way, just sharing my thoughts