The old saying goes: Everyone only uses 10% of what MS Excel can do. But everyone uses a different 10%.
The same goes for Github to a degree. Yes, there are hot paths that "everyone" uses, but also areas where most people never wander and other use daily.
Google Docs doesn't do even 20% of what Office does, but it's a serious competitor anyway. That's because it implements a 5% feature that 80% of its customers use: instant internet sync.
The same goes for Github to a degree. Yes, there are hot paths that "everyone" uses, but also areas where most people never wander and other use daily.