It's more like bringing a shopping cart onto a city bus, when the bus company said "bring all your stuff! we love it!" doing this for years with no problem, the bus driver says nothing, and then one day the bus driver says "hey, you've been causing a ton of problems with that shopping cart, you need to stop." Surprise seems entirely warranted.
I can't seem to find any posting by GitHub saying "yes! please use our free service as your git-based package manager's backend!" Advertising "host your code and assets with us" doesn't suddenly mean that it's justified to say "fuck it, GitHub can be our CDN".
Obvious in hindsight, but if you grew up from a little project to a big one, built so that your "users" are cloning your git repository, is it really clear that you've transitioned from "hosting source code" to "using it as a CDN" sometime along the way?
It's not like these guys thought, "Well, we really should use some dedicated high-end host for all our traffic, but we'll use GitHub because it's easier."
