Some popular browsers are supposedly "open source" yet it appears no browser user longing for saner times has ever tried reversed this change and recompiling the browser for their own use. No third party cookies by default.
The most fascinating thing IMO about so-called "modern" browsers is that even when their vendors publish source code, "99.9%" of people will not even attempt to make changes, even something as simple as changing a default from "on" to "off". It's like the software is stamped with "Read Only" or "Do Not Touch" and "99.9%" of people dutifully obey. The "0.1%" appear to be very conservative with the changes they make.
For example, if it was possible to disable auto-loading of resources, I might actually use these "modern" graphical browsers for tasks other than commercially-oriented transactions. Cookies are only one problem with these browsers.