It does seem a bit high touch, but don't I also have the alternative of just cloning third party code into my repo and bazelizing it myself? I've certainly seen that done, and it's what Google does internally as well.
It's possible and what I've done quite a bit when using bazel but it makes code sharing very difficult. I think the internal desire, from google, is likely between tensorflow and cloud wanting to ship code easily to the OSS world. One of the reasons PyTorch is taking off is because people can build it easily!
