I never used bazel so I can't comment on it. But your argument is invalid. Just because some large scale codebases use cmake doesn't mean it's the better choice. It just means cmake is workable at these scales. But many things that are workable are very far from good
Technically CMake is still not official way to build Boost libraries. A link to latest docs: https://www.boost.org/doc/libs/1_88_0/more/getting_started/u...
While it might look like technicality the number of projects that kept their own build systems is substantial. I would say there are dozens open and many more not so open build systems out there that support large projects and organizations. I don't see anyone rushing to "rewrite it in CMake" anytime soon. At least in gamedev where I work.
https://github.com/llvm/llvm-project/blob/main/llvm/CMakeLis...
How many active contributors does LLVM have? Hmmm
https://github.com/pytorch/pytorch/blob/main/CMakeLists.txt
How many active contributors does PyTorch have? Hmmm
https://github.com/boostorg/boost/blob/master/CMakeLists.txt
How many active contributors does boost have? Hmmm
I could go on...