Still works.

Unfortunately, yes. But it still works and rocks.

uBlock Origin has kind-of-similar (but not quite) functionality where you can block by domains, but it is not as granular (it is called "Advanced" something IIRC).

Yeah, the only similar replacement I know of is noscript. For me ublock origin + cookie autodelete + firefox strict mode is the 90% fix for now. Mostly set and forget without the maintenance of umatric and noscript. Tho, I am kind of surprised no one has forked umatrix and continued developing it