Being sick and something distracting you from it long enough to not notice being sick isn't really addiction. I don't even like Nethack that much and some years ago I played it during a bad stomach flu to prevent myself from vomiting all the time.
We are talking about someone who plays Terraria for so long their health degrades and they don't even know it until they stop.
In a similar vein as those people who played videogames until their legs degenerated.
Psh, that was nothing. All they had to do was hide for a few seconds and they recovered completely.
No, what this is like is that one time where a kid accidentally shot himself because he played games, which was plainly obvious, as the console was
only three rooms away. In this case, the gun is illness, the console is Terraria, and the analogy is fatally flawed.
Point is, I've played games while ill to avoid constantly thinking about being sick, and I've developed little illnesses like colds, etc. while playing and not noticed. It isn't a sign of addiction; the same thing happens to me with books, interesting films, surfing the internet, biking, etc. Games occupy your attention, which naturally means that other things won't be instantly noticable. Now if it was less that/joking and more 'wow I just noticed that I'm 50lb underweight and have a hacking cough', it would be a problem.