What did you expect, it's only been a few months. There's tremendous inertia when it comes to build systems, people don't change them on a whim.

With the fancy distributed bits what's the win I get using Bazel? Maybe it's simpler, but if I already know another system then why switch?

Simple, repeatable builds, almost no learning curve. I do agree that this is a vastly less potent value proposition than "build your C++ in minutes instead of hours", but it's a start. I think Google will offer the distributed cloud piece for this at some point. They'd be stupid not to.

It takes years for a new build format to be widely used.

There are many more important thing holding up wider adoption before the lack of distributed support becomes a issue: Windows support, how hard it is to get working on ARM, etc etc.

TensorFlow is it's own thing.