Yes, I understand that you can post only a link and have the link appear within the body of your post. In fact, you can have several links appear there and also add an image if you remove the resulting link that populates the description field automatically upon first insertion of a URL.
Posts can be shared in this way, but images that accompany the content being shared also vanish when the URL is removed from the description field. What is likely to happen is that users will quickly become frustrated with the fact that the descriptions they are sharing are broken, completely unrelated to the content that they are sharing and/or poorly formatted as to appear messy. They may then take it upon themselves to grab the nice image that is available in the story that they wish to share, upload it themselves, insert a proper title and description and insert the URL into the body of their post. This is a regression which encourages users to upload images that may be copyrighted into their own accounts in order to nicely format a post that they feel is substantive and worthwhile.