I once listened to Alexis give a lecture on the founding of Reddit. One of the more memorable points he made was recalling when they found "Digg". They were still in development, and someone had sent them a link. They spent 30 seconds looking at it, then said "cool", and kept on working.
My own thoughts is that the competition turned out not about features, but community. One might have thought Digg had a big leg up, because they basically had Kevin Rose using his role on Tech TV to promote it. However that was also a disadvantage. Eternal September is the death of most online communities, and they brought it on themselves. Reddit fortunately had pivoted to a platform for communities (sub-reddits) so as they picked up steam, the bad network effects were mostly concentrated to the default subs.