Pinterest does not like URLs in descriptions

Pinterest can be such a fun place to post pictures you either take yourself or find on the web. Creating creative boards that you can fill with pictures displaying your interests is easy, and sharing your personality through visualization seems to be the latest trend. Although Pinterest will allow its users to pin from a Browser plug-in or from a website through the “pin it” button, you may notice that if you copy and paste the title and url into the description box, you will get sent to a Pinterest jail-like pop-up. This pop-up will remind you of Pinterest’s etiquette or even warn you that what you are trying to pin may be spam and therefore they have protected you by not repining the photo, if you then try and repin the post with just using the title, the pin will go through as normal with no issues. Notably Pinterest allows businesses to provide a currency within the description of a product they want to pin and Pinterest even shows the price in the corner of the picture and yes, if you click on the pin itself the page it takes you to comment will show the original domain in the top right corner. However, it is odd that Pinterest won’t let you have the URL in the description and if they do, you can bet it will be once before our friendly reminder pop-up will appear. Is this because Pinterest wants to keep you on their site as much as possible? Or are they truly trying to protect us from spam? Either way, would you as a Pinner like the ability to pin a photo with a URL added in the description without actually having to go directly to Pinterest to do this?