For a court to have jurisdiction means that its word is law. It means that the parties of a case are subject to it’s decisions.
This right to subject an individual to a court’s rulings, does not come from whether it is reasonable or fair. It does not come from whether it is convenient for them to answer the complaint or whether they are present in any given location. The right of subjugation derives directly from the individual’s consent.
Historically, this consent to the governing body has been implied through one’s presence in the territory that it controls.
But, what if the actor has no body? What if the suit is against a company which does not exist in physical form, but merely acts through it’s agents, through computers, telephones, etc. What then is left to determine to who’s rulings it is subject to?
Well, all that’s left is it’s Actions, and indeed, what better a test could there be? Is it not perfectly logical that one be held responsible for their actions in the land where those actions occurred? Is it not the ruler of that territory who is charged with enforcing the laws? Would, as Justice Hugo Black said, it not deprive that state and its residents of their right to self-rule?