I suspect it was because your comment was quite unconstructive, and comes across as a mildly sarcastic taunt rather than a genuine question. If instead you had

I suspect it was because your comment was quite unconstructive, and comes across as a mildly sarcastic taunt rather than a genuine question. If instead you had explained why you disagree with the parent poster and offered some information on how best to define a disease, you most likely would not have been downvoted.