Digg.com was a link aggregate site that predated Reddit, and was more attractive to users based solely upon its relatively sleek UI.
After some years of success, Digg made several changes: obfuscation up votes and removing down votes, and a new UI to match the reduced features. As a result the majority of the Digg user base and content creator sphere migrated to Reddit.
This resultant swell in Reddits userbase led to app creators brisging the gaps between reddits relatively brutalistic UI and the experience sought by laymen (i.e. non programmers crowd). As you have seen the decision to alienate third party applications has led to a new backlash against Reddit.