I think there's a big abstraction gap between what we use domains for and what they were supposed to be used for, in a way that we shouldn't assume any ownership only based on the domain itself.
For instance you can have a number of sites that use separate domains but are owned by the same entity (N domains for 1 party). You could also have the same base domain being used for several unrelated parties, think hosting a store on Shopify (1 domain for N parties). This is so ambiguous that even inside the browser you have two different implementations on the way you handle this attribution, one for cookies and one for Single-Origin Policy.
There's a good write up about this problem at https://github.com/sleevi/psl-problems. Sometimes I wonder how the web got here with the amount of kludge that we have to carry.