You cannot even mention an altcoin without being shadowbanned. It happened to me. Mentioning an altcoin isn't the same as promoting it. You might want to point out that some users are flocking to Ethereum because of the fees.
The r/Bitcoin moderators are running a bot that has a list of accounts whose comments or posts it automatically removes. It's essentially being shadowbanned from that subreddit alone, and the users in question are not notified of that. Want to test? Make a new account and make a comment against Bitcoin Core or pro-blocksize increase, and see what happens within a few minutes.
The mods of r/Bitcoin have also personally tried to get me banned from reddit through untrue accusations to the reddit admins (they tried to get me globally banned for "doxing" theymos, notice the timestamps: http://i.imgur.com/THhruNm.png when I called him by his first name, which he himself publicizes on his LinkedIn page as associated with his handle "theymos"). Obviously the ban had no merit so it did not stand up to admin scrutiny.
- A bot that automatically removes users' posts and comments without actually banning them or telling them the items are being removed (this is a subreddit-specific "shadowban", though it's not a built-in feature of reddit it has the same effect)
- Moderators that eagerly attempt to ban all dissent, not only from their subreddit but from all of reddit
They are both wrong, both unforgivable, and both forms of censorship. Just ban people you don't like from your subreddit, no need to code custom bot features or try to lie to the reddit admins to accomplish political goals.