liberals typically reserve systemic explanation to exonerate individuals willingly carrying out the functions of a rotten system only when they see themselves in the subject ("a decent person doing their best while participating in a corrupt system") https://www.theatlantic.com/ideas/archive/2020/08/give-kamala-harris-break/615127/
they do not extend a systemic explanation to their political rivals on the right. Cheney & Rumsfeld were not viewed as the inevitable product of a system created to maintain American empire (because doing so might question their own role in empire) but rather just some bad dudes
the system itself understood as either too inevitable or overwhelming to direct your ire towards (might as well protest mortality while you're at it, goes the pragmatic liberal logic). the system is as natural as the sun: the cause of our existence, not to be stared at directly
a Peter Beinart is not afforded such a national profile or platform as he is if he too often or forcefully took issue with the system itself. the same systemic forces that produce a Kamala Harris also produce a Peter Beinart. it is little wonder what is produced is justification.
a justification, typical to liberalism, that suggests, well, aren't we all actually guilty? do we not all participate in systems that damage human life?"man makes history but not under conditions of his own choosing" right radicals? so how can you hold the system against someone?
sure, Harris is absolutely the product of a racist, carceral, punishment-oriented system. but she was also a willing functionary of it. sure, another Harris likely would have been produced in her place but at what point does this become the liberalized "I'm just following orders"
what distinguishes the liberal from even squad-type social democrats is that the squad-types have at least a critique and a pose of opposition to the system itself. a critique of ideology. that's the bare minimum to being afforded any sort of justification in participation.
otherwise, yes, you're stuck with the ideological hegemony of the mid-00s - still largely hegemonic today - where it is assumed plucky, presumably well-meaning technocrats like Obama, Harris, Pod Save America-types etc. can affect change by being 'just better, smarter people'
a challenge to, and a possible replacement of, this "all will be ok with the right smart and nice people in charge" ideological presumption cannot be made without a sharp and direct critique of the people who willingly carried out the injustices of the system. so here we are.
more personally, I see very little that is redeeming, charming or admirable in Kamala Harris (she opposes the death penalty? ooooh wow). in numerous accounts she appears to be a person who enjoys inflicting righteous suffering on the vulnerable, largely ego and power driven.
just as with a Buttigieg, there is no vision on offer, no set of specific problems that need addressing. rather, there is simply a boat in need of steering & we are to trust in their wisdom to steer it wisely. it reflects, & speaks to, the lifeways of upper-middle class liberals.