Blocking domains works right now but what if Facebook register a new domain? Or a thousand new domains? Or they proxy traffic through a site owner's domain? What's needed is a way to block Facebook's privacy invasion regardless of the tech they use. That is unlikely to be a problem solved by tech. It needs enough people, including governments, to tell Facebook they're unhappy with Facebook's activity.
As far as the cross-site tracking goes, they'd actually need to get all the other websites to update the facebook JS code they include, and it would only work until the tracking blockers updated their lists again.
I agree that tech is the wrong place to be solving this problem, but it can work in a rather cludgy way.
Just in case you weren't aware, uMatrix has been deprecated and will receive no further development, including fixes. It still runs fine now, but it may not in the future.
There seem to be several forks, although it doesn't look like there's much consolidation on merging PRs into any specific repo. Hopefully they don't just splinter off and end up fragmented and neglected. :-\
uBlock Origin in advanced mode is gorhill's suggested replacement. If you have never used uMatrix before most likely uBlock Origin is what you should be using, and can easily accomplish the "globally block facebook domains" either via blocklists or manually via the advanced mode.
