Maybe because tons and tons of software build with GNU make, not with Ninja, and if you want to be able to build that software, you need GNU make?
Also, Ninja by itself is not really a replacement for GNU make. Rather it's a tool one can build such a replacement on, so the comparison is a bit off to start with...
Also, Ninja by itself is not really a replacement for GNU make. Rather it's a tool one can build such a replacement on, so the comparison is a bit off to start with...