This will break so many things, that's not even funny. I can already hear customers complain their bank doesn't work on chrome. Maybe this will drive Firefox adoption? (Let me dream please)
It only covers third party cookies, not cookies in general. They aren't used that much except for ad tracking. For the few other use cases that exist the offered workarounds are pretty good and more secure than a general wide cookie.
Safari blocks third-party cookies by default and introduced a new Storage Access SPI so third-party sites that do need cookies can request explicit user permission. This is all part of Safari’s Intelligent Tracking Protection.
Firefox doesn’t block third-party cookies by default because that can break sites that haven’t been updated to use the Storage Access API. Instead Firefox’s Enhanced Tracking Protection blocks cookies from a blocklist of known trackers and all other third-party cookies (e.g. new trackers or legitimate use cases) are isolated using Total Cookie Protection (which has the inconvenient acronym TCP).
Total Cookie Protection uses double-keyed cookie jars, so cookies from analytics.example included in an example.com page are placed in a separate cookie jar from analytics.example cookies included in an example.org page. This allows both sites to use the same third-party analytics service, but the analytics service sees different cookies for each site and can’t link the cookies to one user’s browsing behavior.
