The free-as-in-beer parts of github.com are not (guaranteed to be) a core business of Github either. Just look how lousy Atlassian is with bitbucket.org; their core business is Stash.
Um, what? Bitbucket was around long before Stash was. Bitbucket was a startup and acquired by Atlassian back in 2010, with Stash's first release not happening until 2012.
Atlassian's core business is Jira and Confluence. Stash is pretty much an also-ran at this point. (Bitbucket, the free product still looks better and has more features - Stash has literally no reason to exist unless your company is terrified of the cloud - and then, Github Enterprise is superior in every way.)
Stash is not just if your company is terrified of the cloud. It's also perfect when your customers are extremely risk averse and will not even bring their business to you if you host anything outside your own company, which of course has to be security audited into infinity.
A company I used to work for once had a customer demand (and pay for the purchase of) a separate HPC cluster just for running the simulations for that customer. Because we could not guarantee 100% that it was impossible to circumvent the access controls on the regular cluster, which only had users from the same company, but not all those users had clearance for that project.
Stash may not be the cash cow that JIRA is but it seems to make more money than Bitbucket does. My assessment of Atlassian's approach to Bitbucket is based on me observing them handling tickets for it (stonewalling for years), and other users' observations on the difference in the way they handled BB vs Stash. The silence from Atlassian on some years-old Bitbucket tickets is deafening...
Let me just drop this here: https://bitbucket.org/site/master/issue/8436/not-all-github-... shows that Atlassian can't even be bothered to make it easy for people to migrate to Bitbucket, their repo import tool cannot handle the pagination the github.com API does. They can't be bothered to let people paying to Github pay them instead. My guess is: they don't care about your $5 (or whatever puny amount it is) payment for private Bitbucket repos, they care more about the $XX,000 they get from every Stash license sold. And mentions on Bitbucket tickets make it look like Stash is quite popular in some corporate circles.
NB: GHE may be superior in every way, but does it integrate with JIRA as well as Stash does? What if you've already invested in JIRA and want to add a repository management platform? (Also, don't underestimate the portion of the market "terrified of the cloud".)
That's a good point, but Google Code was never a core business of Google.
Github would have to undergo a serious shift before hosting code repos isn't a core business function.