I can't claim to be a libertarian, but I don't think minarchists claim to espouse an economic system at all. You may be thinking of left market anarchists. And I'm pretty sure some libertarians will make their point with private force applied to consenting market participants used to secure their capital markets.

Also this isn't meant to be an exercise in ideological critique so there's no need to defend what "many anarchists" think. My post was just there to demonstrate how many strains of anarchism there are and how few goals they tend to share. Also it's partly to remind folks that there are more than just Ancoms and Ansocs out there, even if they tend to be the most vocal in tech spaces.