Our Blockchain would grow more if we would allow those who do not have accounts to post comments

This is a brilliant idea. Very insightful. I've thought of this possibility too a couple of times. I am sure it is possible. Guests can make comments, just that they won't be rewarded. That alone should be good enough reason for them to sign up and come on board. Even when one is not getting much upvotes, knowing that some people are reading your posts could be enough compensation, although the upvotes are very important.