Looking at https://github.com/facebook/buck/graphs/contributors it seems like there hasn't been any commits to the Buck master branch in over a year. I loved using Buck in 2014 when it was the best open source Blaze. At least until 2015 when Google made Blaze open source. So why didn't Facebook give up on Buck sooner? Perhaps it's for the same reasons I now use make. I saw how angry Bazel made many open source people. I suspect part of it is that asking people to install a new build system just to use your project is a big ask, and it's an even bigger ask when that build system depends on things like the JDK. If Facebook rewrites it all in Rust and manages to ship single-file executables similar to what I can already do today with GNU Make, then it might be a positive improvement.