While it is desirable that the build server becomes one of the focal points in your CD pipeline, also consider that the process of building and deployment should not come to a standstill in the event of a breakdown of the build server. For this reason, the builds themselves should be as robust as possible and repeatable on any host.
This is fairly easy for some builds, such as Maven builds. Even so, a Maven build can exhibit any number of flaws that makes it non-portable.
A C-based build can be pretty hard to make portable if one is not so fortunate as to have all build dependencies available in the operating system repositories. Still, robustness is usually worth the effort.
