Github definitely extended git to a far less technical audience than basic git came from. Emailing patches or connecting to others' remote hosts to pull changes was too much complexity for many customers.
Pull requests, CI platform, authentication that is not PAM etc.
Is that any of that something that cannot be easily replicated?
A lot of work maybe, and required a vision to do so initially. But straightforward work that MS could easily do it, and of course other small companies have replicated it too.
I'm still a paying customer from somewhere before 2010, don't use it consistently but I've got a ton of things in there. Every time the anniversary rolls around in November I ponder how much effort to move off it for the not insignificant cost, but then the desire fades until about the next November :)
I'd say damn near 20yrs. I used it quite extensively about 10yrs ago and it was an odd one then, but was very useful for the purpose we had (semantic validation of XML payloads).
