When we started, buildkit was still experimental. Personally I'd like for `pack` to be able to jettison all the code that has to deal with the Docker daemon, it's a bit of a PITA, and buildkit looks to have significant improvements in at least that area.

I'd note that the frontend there is for "v2b" buildpacks -- the previous generation of Cloud Foundry buildpacks. The CNB lifecycle has changed a fair amount from the v2a (Heroku) and v2b designs.