What's the point of deleting cookies if most browsers block third-party cookies?

I was trying to get my browser setup more private and in the process I have learned a lot about how cookies and tracking on sites like Facebook, Google etc. works

But there are still some things I think I've missed.

For example I have learned that using containers and cookie auto-delete extension is basically useless now because even browsers like Edge allow users to block third-party cookies.
So If I understand it correctly it means that Facebook cannot access …

browsers cookies party privacy third third-party