Ceteris paribus generalizations applied to natural systems aren't the same as those applied to society. The latter are liable to have normative connotations.

Did I say that pareto optimality equals neoliberalism? That's a strawman, I think. I certainly don't claim to be an expert on this, and I haven't read much on pareto optimality. But I suspect that that principle is currently used mainly to justify libertarian, laissez-faire policies. It's a tool in that arsenal since the economist would say it's wrong to sacrifice the rich to help the poor (to redistribute that wealth). That use of pareto optimality would abstract from the moral and historical contexts in an obnoxious fashion, and that's what I'd object to.

Maybe pareto optimality can be used for anti-libertarian purposes. It's hard for a nonexpert like me to tell because of how circuitous pareto optimality is stated, which is suspicious in itself. It's not just a question of "jargon"; rather, it's how indirect the principle is. I mean, what exactly is pareto optimality, stated plainly in just a few words? Is it even possible to state it like that?

Here's one statement of it:

"It describes a situation where no further improvements to society's well being can be made through a reallocation of resources that makes at least one person better off without making someone else worse off."

So the emphasis is on making people better off only in ways that don't make anyone worse off. Stated plainly, the point is that if we want to improve things economically, we shouldn't sacrifice anyone in the process.

Then again, what if in the real world there are always bad actors with too much stuff on their hands (because their possessions are ill-gotten)? Why should making them economically worse off to help the poor be off the table for the government (as in the case of progressive taxes)? Why would that be an immoral sacrifice rather than a case of redistributive justice? How does pareto optimality help us distinguish between unjust and just redistributions of wealth since it abstracts from morality and history?