I agree that in principle a strong portfolio is a great way to communicate software development skill. What I don't understand why he feel "now" is different.

I agree that in principle a strong portfolio is a great way to communicate software development skill. What I don't understand why he feel "now" is different. Github isn't exactly new and there is plenty of time for others to innovate in this space. Why haven't we seen this effect already? If it could happen fast it would already have happened. Why won't it be a slow taking a decade or more like the proliferation of Social networks?