Bazel does the opposite of rebuild-the-world. That's more of a CMake thing (rm -rf build && mkdir build && cd build && cmake ..). Bazel won't even run tests if the code the tests depend on have not changed. A lot of thought went into Bazel. It caches everything it possibly can.

> I'm already getting flak from Linux distros maintainers because I use some vendored header-only libraries and not system ones so I don't see how that is even supposed to work.

That's where you use autotools. It has been around long enough that every package manager knows how to deal with it. For most C/C++ programs, autotools is all you need. You should learn it because it's not going away.

"the IDE" (like VS project files) is definitely not cross-platform (although it can be), but not everything needs to be cross platform. For game devs building on DirectX, for example, it's completely pointless to support other platforms when the runtime depends on a single platform.