I don't think it's etiquette, but rather disinterest. As soon as a comment is specialized, it has a smaller audience and hence draws from a smaller pool of pote

I don't think it's etiquette, but rather disinterest. As soon as a comment is specialized, it has a smaller audience and hence draws from a smaller pool of potential upvotes. The problem with Slashdot you cite is interesting. It is related to more general problems with crowdsourcing. Wikipedia is successful but sometimes you really notice that an article is written by different people with different viewpoints. Similarly, a "democratic" model for science, where instead of peer review papers are upvoted, does not seem very attractive. Perhaps this all boils down to the notion that neither truth nor quality are democratic; i.e., the average opinion is not a good estimate of them.