The landwhales are probably bitter they can't get Chad and so take out their not being a top tier Stacy rage on us.
After all they can't go rage at the cool, hot, Chad type of guys because Chad telling them "LOL, go away landwhale" would actually "hurt".
Whereas if "we" say it in response to their hate they can just rationalize to themselves "Oh look an ugly bitter misogynist inkwell thinks I'm fat and undateable, how cute!" and brush it off.
So we're a better punching bag for their fragile egos I guess you could say but if they simply spent all the time they do hating on us in the gym working off those extra pounds instead then maybe they'd get over their own "bitterness" as then maybe just MAYBE Chad would then actually want to date them?