V4 was definitely the tipping point and nail in the coffin for Digg. However, once the Digg community became to large it became difficult to find interesting stories about a particular topic. At the same time twitter, hacker news and many of the sub-reddits became great ways to discover unique content.

So a combination of poor product design, a selling out the Digg community and availability of alternatives killed Digg.

I would argue that the "big break" was actually a bad thing for Reddit. The massive influx of disenfranchised Digg users contributed to the decline of quality on Reddit big-time.

Agreed. People still would have gone elsewhere even if Reddit didn't exist.

Guess I will be the first one to admit that I have no idea about Digg's development versions.

So the question is: What was the big deal with v4?