Now there are massive blocking of Twitter accounts.
Most often, block accounts when you to use mass-following. Blocks is forever!
Also do not use hashtags #ICO #Cryptocurrency etc
Be careful!
UPD
Some accounts of my friends that have been blocked marked "forever" are now unlocked
But anyway, I think we need to be careful
Mass following is a tool to deceive and cheat the system and twitter has a system to catch those accounts, everything here is automated we should all be careful to follow their guidelines less you get your account blocked without recovery, so take heed.