Whenever you choose the “Login Through Facebook” option on any website or mobile app, you expose every other account where you ‘logged in through Facebook’ including Uber, Snapdeal, Zomato and Foodpanda among the rest.
The author probably meant to say that's it's way way way more easier to get seed funding than ever before (besides probably the pre-dotcom burst era).
Secondly besides a prototype you also need a little amount of validation in the form of paying customers or small loyal user base and a good amount of connections to pull of that funding.