Oh, Linux Mint mixes Debian and Ubuntu packages by default? I was under the impression that there is Linux Mint based on Ubuntu and Linux Mint Debian Edition based on Debian.
> Secondly, they are mixing their own binary packages with binary packages from Debian and Ubuntu without rebuilding the latter. This creates something that we in Debian call a "FrankenDebian" which results in system updates becoming unpredictable
This is interesting because Debian itself encourages derivative projects to use their binary packages[1]:
> For those derivatives that re-use Debian binary packages, add some source packages and modify some source packages, where possible we encourage them to use standard Debian mirrors and add a second repository containing only the source and binary packages that have been added or modified.
Or maybe they don't encourage that behaviour but still give guidelines in case you want your derivative to work that way? I'm not 100% sure.
I can only speak for myself, but I love GitHub because it's easy accessible for me. When I was learning how to use git and code in general (well, I'm still in that process to be fair), it's great to have a visualitation of what you're actually doing. It's even better when that interface is well-designed (at least I consider GitHub to be great UX), so you don't have to learn using another UI on top of all the new stuff you already learn as well. I think that's a factor you underestimate when you've been working with revision control and code for a long time.
Additionally, the collaboration aspect of GitHub is great as well - As it's a big plattform, a lot of developers already have a GitHub account and it's very easy to contribute with forks and pull requests. Submitting patches via mailing lists isn't everyone's cup of tea.