I agree. It has something to do with the archetypal role of the Host. That’s why I don’t like potlucks. If I am inviting everyone over then I believe in supplying all the food and drink for my guests. And I enjoy doing so. There’s a privilege and joy in sharing bounty with one’s guests.

Of course this type of formality can be dispensed with in a romantic relationship after you get to know each other and if you relate better on an egalitarian basis. This is entirely dependent on the personalities of the couple.