I think that's a problem for companies that owns multiple domains and want to track users between those. Browsers shouldn't have to help with that, but rather i

I think that's a problem for companies that owns multiple domains and want to track users between those. Browsers shouldn't have to help with that, but rather implement the most simple and efficient way of protecting their users, as long as it doesn't make the users' life more complicated. That's what should matter: users, not companies.