Early reddit was very similar to HackerNews. One front page where users submitted interesting links and stories. Then slowly subreddits started to get introduced, like "/r/science", "/r/programming", and "/r/atheism". Already very early people didn't like this change and created /r/TrueReddit. Read their rules and you can see how similar to HN this is "only interesting stories", "do not editorialize the original title" etc. However even /r/TrueReddit shifted heavily towards politics (i.e. short by top -> all time and see which stories get most upvotes). After that /r/TrueTrueReddit for people who were trying to maintain the same spirit. But it is dying now more or less.
Many many small changes had to happen before it downgraded into what we see today [0].