I understand some web site owners like the idea of having unique content on their site and it is their right to demand it. However, if it is a good quality article which is useful for their readers, then this is beneficial to them as it can attract more visitors through social media.
Is there a way of searching for blogs in Google which don't insist on unique content for guest posts? I have tried - keyword "write for us" or - keyword "submit guest post" into Google. I then look for blogs ranked high in Alexa.