I don't know enough details to fully describe the discussion. The meat of it though, as I understand it right now, is ...
- packages are still on the v3 schema because the old website doesn't know any better (and cannot be updated)
- libraries are however already on v4.
- thecrawl crawls packages, https://github.com/packagecontrol/channel crawls libraries (?)
- there is crawler-like tech in the PC client package to resolve package
Perhaps more. But there is some consolidation that can happen here, especially once the old site is no longer needed.