Because they can "own" your website in terms of control, yet not actually own it under that specific concept. E.g. Google threatens taking away ad monetization if you don't remove certain "questionable" content (according to them). They don't own your site, but in that case they're controlling it.

And here it is in action:

https://milo.yiannopoulos.net/2017/08/google-threatens-conse...

I can accept a person closely related to and caring for their land to have some notion of ownership,

but a corporation who only uses land without consideration for it or the local animals that depend upon it, and only cares for profit cannot "own" something that is essentially timeless and really belongs to noone but the universe. Its like ants squabbling over owning mount everest.