We've used blocking in response to our project and community being targeted with harassment, libel, racism, trolling, etc. rather than proactively blocking many servers. We tried to only block servers where the admins were either supporting the toxicity or bypassing blocking.
Our approach was working fine until the harassment massively escalated in April with multiple severe swatting attacks and threats of violence. A YouTuber closely involved with Kiwi Farms escalated it much further in May.