Incorrect. Most 1,000 comment threads are in the default subreddits.

Using BigQuery to group the number of threads by subreddit:

https://docs.google.com/spreadsheets/d/1_bL0dVn3z2R-pUkWuWNr...

   SELECT subreddit, SUM(num_comments >= 1000) as num_comments_gte1000
   FROM [fh-bigquery:reddit_posts.full_corpus_201512]
   GROUP BY subreddit
   ORDER BY num_comments_gte1000 DESC
   LIMIT 1000