well to play devil's advocate, for most users on Steem a "crosspost" doesn't appear as a post at all, it is just a text link to another post. Only on steempeak does it actually appear as a post, and steempeak is still only a fraction of the daily users that steemit has. It really isn't particularly surprising that people are flagging cross posts. Put yourself in the shoes of a steemit user (I know, those are painful shoes to fit into). An author you follow has published six posts into your feed, five of which are just links to the first one. How is that not spam? Do you really think a text link to another post is deserving of upvotes?