Allow Override for not recommended subreddits

[Danura30082]

I tried to subscribe to an author in r/BestofRedditorUpdates, but I got the following message:

"u/UpdateMeBot is not suited for subreddits like r/BestofRedditorUpdates. It only works well in subs where the original poster of the thread will post a follow-up as a new thread. It's also possible this subreddit doesn't exist."

While I appreciate the warning, I would still like to be able to receive updates.

The relevant code seems to be if subreddit.is_blacklisted:, but I don't understand why some subs would be blacklisted.