This is defense in depth. We are way too lenient on the people who are not safe enough to be in society IMO, so it's good to have another mechanism. Recently, it's even worse than it's used to be... e.g. in Seattle they quickly release people back onto the streets after multiple separate violent assaults.

I think the incarceration for drug crimes and such should be stopped, but I am also a-ok with stigma following repeated and/or violent crime. I personally think people who have repeatedly shown to be too dangerous to live in society should never be released into said society, but if that mechanism is broken due to "compassion", at least I prefer to never interact with them.