In what world is 12.5% of revenue "irrelevant"? The 37.5% business revenue is just 3 times as much (so almost as irrelevant), and Enterprise is only 4 times is much (again, almost as irrelevant).
Unless .. all github revenue is irrelevant for Microsoft - which might be true, for all I know.
I bet it's much less than 12.5% now (since 2016). Also, individual user revenue is revenue that public investors value less than revenue from businesses, because there is perceived to be a much bigger overall market (and therefore more future potential growth) in selling to businesses rather than individuals. And growth is what matters for the stock price.
Source: I am the CEO of Sourcegraph and consider similar things.
What I've always found funny about "B2B is more valuable than B2C" is how all economic value eventually comes from B2C eventually, and all the meta B2B tools in between don't really make value independently on their own.
That might indeed be true. GitHub's value to Microsoft ain't the revenue; it's the users, the mindshare of whom Microsoft hopes to capture by luring them toward the Microsoft ecosystem (Windows, Office, Azure, SQL Server, etc.).
As a particular former Microsoft CEO put it: "[…] DEVELOPERS DEVELOPERS DEVELOPERS DEVELOPERS […]". That strategy/desire hasn't exactly stopped, though it's certainly transformed quite a bit over the last couple decades (and Microsoft is finally actually getting somewhat effective there).
Unless .. all github revenue is irrelevant for Microsoft - which might be true, for all I know.