Ankit, Its not good to rate this site as a reviewing site. And of course yes, there are many sites where you will get various opinions on a particular topic by various authors. Say for example Mashable.
But, come out from that zigzag, simply think GPT as a site like Hubpages. where authors has no restrictions to post on a particular topic, though you cannot post the same topic name again. By topic name I mean the title of your content, that title should not match, this is very much taken care of in Hub pages. So, I think redundancy in terms of title may be restricted, but topic or content should not be restricted. As this site is not a personal blog, but a site meant for everyone to express their view on a particular topic.
Please rethink over this ban of yours on redundant topic.
For example If some one post about facebook vs Google+ backing facebook and some other posts Google+ vs facebook backing Google+, then both should be allowed. Restriction can't be imposed for the same.