Not that I agree with the what the poster is suggesting; however, it could also be seen an attempt at enforcement of a social norm. More akin to laughing at the kid(=child) who wears funny cloths, then to burning the witch down the street who put a hex on the neighborhood cat. And, to me, spamming (still) feels more like a violation of a social norm than "Doing something wrong"

To continue with the tailgating analogy used in some of the other posts: tailgating is one of those things that is more on the 'not being polite' side of the coin than on the illegal side -- how many people get pulled over just for tailgating... So, sometimes a person will slow down to punish a tailgater even though it will take the person longer to get to h(is|er) destination. http://cat.inist.fr/?aModele=afficheN&cpsidt=16090318