What Happened To Digg? 4 Reasons Why It Ultimately Failed
productmint.com
Digg failed because of poor product decisions, rising competition from other platforms, internal problems amongst its staff, and users trying to game the system for their own gain.

The similarities are amazing, especially considering Reddit was one of the succesors of Digg. They can now enable other successors by making stupid decissions and alienating core users.

I wonder if this speaks to the unsustainability of platforms like these, or the cycle can be broken by making good decissions.