The place I have used this rhetorical technique (and I'm ashamed to admit I have, 'cause I find it irksome myself), is when I'm posting something I believe is correct or worth considering, but which goes against the overriding sentiment of the site. I believe it disarms people's unthinking, reflexive downvote, though I have only my own experience to draw this from.
Maybe you think this is being "needlessly defensive", but that sounds like someone who's never had a comment downvoted to oblivion only because its sentiment is unpopular.
I'm not really sure why being defensive would undermine someone's point.
"If what you're saying isn't worth potentially being downvoted for, delete it."
The point isn't the negative karma (though that is a motivator for most people), the point is that down-votes mean something is less likely to be read (due to mechanical filtering), or will be read as a troll rather than as a reasonable opinion. People put some stock in the hivemind's opinions.
To reiterate what the post you replied to said: don't hate the player, hate the game.