Search Engine wants to provide valuable information to its searchers, Duplicate content that is not valuable enough has big possibility to show up in the very bad position
It is easy to explain why Search Engine does not like duplicate content. You know that people who search thins in a Search Engine want to get the most valuable information. If, for example most of them do not find what they want, or find too many similar information, then probably next time they will not search anymore in the Search Engine.
If people dont like searching there anymore, it is likely that the company that own the Search Engine itself my loose their market. Of course the company like Google tries hard to maintain the valuable search result to serve its users. That is a simple explanation why Search Engine Hates Duplicate Content. Have you write your own unique content for your blog?