Twitter change its privacy settings and blocking policy. According to the new blocking policy
If your account is public, blocking a user does not prevent that user from following you, interacting with your Tweets, or receiving your updates in their timeline. If your Tweets are protected, blocking the user will cause them to unfollow you.
Previously, if you get spam tweets or were harassed you can block this account which remove the account from your timeline&mentions and do not allow this account to follow you. However, the new blocking policy make this account invisible to you but allow this account to follow and retweet you.
This is terrible since women have received repeated rape and death threats on Twitter and blocking is one of the options for not receiving(The other one is deactive your twitter account which is worse than the blocking solution). Thus, in order to get back the blocking policy and make Twitter safe place Zerlina Maxwell start a Change campaign “Don’t Make Life Easier for Harassers. Don’t Change Your Blocking Feature“. This campaign get 2.528 supporter and it gain a success.
Thanks Zerlina Maxwell for such a great campaign.