I'm aware that opposing radical solutions is in a way conserving the existing solution - and I'm using "solution" generally, I'm not implying that they're any good. I don't want to conserve the current system (though I'm in the UK, so it's less immediately relevant), but I don't want to rashly change it if it means not considering the consequences of those changes.
I've got my own perspective here - I was attacked at school and kicked in the head. A year and a half later, I've had a lot of recovery but it's still completely changed my life.
From my perspective, it was entirely preventable if schools were more willing to expel violent individuals (they had attacked my friend just days before). It may have been deterred if our justice system was less lenient towards under-18s (I was offered "restorative justice" - "talking it through" rings a bit hollow when you've spent the last 4 months off school, barely awake). There is no scenario where talking to him would have been beneficial to me, regardless of how controlled the surroundings were.
That's why this is the one political subject that I consistently talk about when it comes up on HN: It's one where there are a lot of strong emotions both ways, and I see a lot of sentiment that ignores the real human cost of allowing (particularly violent) criminals to continue their actions. There are a lot of strong emotions about radical solutions like abolishing prisons (and hampering schools ability to expell), and there are a lot of strong emotions dehumanising criminals (and treating expulsion as the solution to any problem). People are quick to recognise the harm that one of those positions causes, but rarely see that they're both harmful when done in excess.
So I also feel that it's easy for the average commenter to talk about how "conservative approaches just mean excess harm". From my perspective, overly rash, poorly-thought-out and poorly-implemented approaches also cause excess harm. I'd much prefer this tug-of-war about moving the overton window through extreme policies was put aside so that we can talk about more realistic solutions. And they don't need to be invented in isolation: The world is filled with alternative systems to learn from.
Ultimately putting forward suggestions like "simply abolish prison" is just going to make people dismiss you entirely, not become sympathetic to your cause.
As for why I'm speaking from a UK perspective on a US-centric thread: We tend to import your culture due to a shared language and a lot of shared culture, so in the long run what the US thinks, says, and does is very relevant to me.