As we have stated already, duplicate content has been on Whaleshares before steem2wls - we just make cross-posting more convenient than using masdacs or doing it manually. Any negative SEO consequences could be eliminated by implementing canonical links, that is upon Whaleshares to implement first, not us. Nobody says that canonical posts bring any positive SEO, but contrary to duplicate posts without canonical refs they have no negative effects which makes your argument of "killing the SEO" invalid.