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it says no one can really do anything deliberate to affect your seo ranking
Can competitors harm ranking? There's almost nothing a competitor can do to harm your ranking or have your site removed from our index.
Notice the word "almost"? Some competitors have tried and succeeded with some pretty dark disruptive tactics.
What I recommend to clients who want to syndicate content is that they write a shorter version of the article and include a link to the "extended version" which they host on their own website. It's worked pretty well, even though it is a bit more work. But hey, if you've got something valuable to say, then it's worth it.
The advice is kind of contradictory there;
on the one hand it says no one can really do anything deliberate to affect your seo ranking
on the other hand, if you have say 20 other sites duplicating your content word for word, you will be affected seo-wise