"We have begun to test a product feature to help us identify suspected abusive Tweets and limit their reach. This feature takes into account a wide range of signals and context that frequently correlates with abuse including the age of the account itself, and the similarity of a Tweet to other content that our safety team has in the past independently determined to be abusive.
It will not affect your ability to see content that you’ve explicitly sought out, such as Tweets from accounts you follow, but instead is designed to help us limit the potential harm of abusive content. This feature does not take into account whether the content posted or followed by a user is controversial or unpopular."
This update has been a long time coming, with many abandoning their Twitter accounts due to abuse. After Facebook implemented tools to offer counselling to troubled users, it was only a matter of time before Twitter accepted some responsibility for its users well-being.