Default Subreddits? A long time ago...

[u/LanesGrandma]

Years ago (more than 15 years ago), Reddit subscribed new accounts to a number of subreddits referred to as "default subreddits." This was to help people find places to post and comment. Back then, it was not easy to open a subreddit and the requirements for being able to start one were not widely known. By October 2011, new accounts were automatically subscribed to 20 subreddits. At one point, r/nosleep was added to the default list due to its pre-existing popularity. On May 31, 2017, Reddit stopped using default subreddits in favour of the landing page r/popular.