If authentication is too complicated for the average developer to understand, other businesses will become more willing to use Goog & FB as identity providers.
There's also generally a lot of FUD around authentication because most web developers don't understand information security well enough to weigh the pros and cons, so technical discussions usually devolve into, "Google uses it, so it must be solid."
There's also generally a lot of FUD around authentication because most web developers don't understand information security well enough to weigh the pros and cons, so technical discussions usually devolve into, "Google uses it, so it must be solid."