Honestly I was just being rhetorical.

Buildroot really isn’t bad but it’s not totally solid and it’s not hard to mess it up either by not thinking or not reading the documentation.

Changing the config and rebuilding without cleaning is the most obvious thing although the docs explicitly tell you not to do that so that doesn’t really count.

Certain compiler build settings can result in a failed build.

It’s really only meant to be used for making cross compilers anyway and the root image generation is a sometimes useful thing. Personally if I want a rootfs it’s easy enough to make one from scratch.

Second that question. If you don't do product lines with varying platforms, buildroot is much easier.