When did reddit change their frontpage behavior? Previously you'd only see posts...

asdff on June 27, 2019 | parent | context | favorite | on: Reddit has quarantined /r/The_Donald

When did reddit change their frontpage behavior? Previously you'd only see posts from the default subreddits on reddit.com, now you have a chance of seeing something gamed from an alt right subreddit? Why did they ever ditch the whitelist model?