One could assume that they are either simply lazy or incapable of designing such a system on their own. By taking a look at their "index" which consists of one giant directory in a single GitHub Repo, one could indeed argue that it's a mixture of both.

There are so many (big) companies out there using cocoapads for their app development, getting a few to sponsor the hosting bills should be more than doable. A lack of funding is really no excuse.