It's a set of trade-offs. I could run my own cloud stack and all too but I don't want to deal with it.

I could push to a self-owned git repo, but bitbucket and github have lots of nice tools already built around them. When they have issues with their servers/disks, most of the time I won't know and don't have to do anything.

Now, by all means, have contingency plans. Keep pushing to that self-owned git repo, have back ups and such, but I think people just don't want to worry about things.