“seemed like a good idea at the time” 
when dt was started, rt was still closed source (free to try yet would crash with more recent glibc such as gentoo had in the day). there was rawstudio, a small project that kinda hosted the beginnings of rawspeed, but the results i could get with that were limited. something about tone curves and default settings, i don’t quite remember. it had the most incredibly clean code base though. other than that there was ufraw and a gimp plugin for it. so from some angle you could say that there was simply no functional raw workflow tool on linux.
if you want more historic miscellanea: the first version of darktable was simply using ufraw compiled into the same library 8 times with different name, so it could be run by 8 threads in parallel (ufraw used static state variables…). though this was very quickly replaced, it predates the abovementioned blog post…