* does not support Windows fully.

* requires users to install a large amount of dependencies (both JDK and Python 2) just to build a C project.

* requires user to manually write BUILD files for all third party libraries.

* has no way to discover existing libraries on the system.

* no integration with IDEs (most pertinent to Windows users).

Therefore bazel is not going to win over CMake any time soon. Not because it is worse, but because Google's needs are different from everyone else.