CF decided to switch and unify the disparate CI approaches to form a unified pipeline.
Unfortunately there were some problems with some of the Go CD design decisions that, in our opinion, make it very difficult to use.
Cloud Foundry projects and their tests needed to run on different architectures, different platforms, against varying underlying Iaa Ss before being tested that they could be deployed fresh while also remaining compatible with upgrades from previous versions.
Finally, these projects need to be packaged up in various ways to create multiple derivatives end products.
Interesting features like timed triggers and synchronizing usage of external environments are modeled in terms of these, rather than as layers on top.