Why is drag and drop so hard?

Drag and Drop has been a part of HTML Spec forever and has been supported by all the major browsers. It is supposed to be an intuitive and simple API and works out of the box, just like the example below.

BUT it doesn’t. As soon as you add a specific use case it becomes useless and that’s why there are tons of libraries out there to do the job instead. This is a rant post to discuss HTML5 DnD API and compare alternate libraries… more to come…