[collingreene]

>I don’t understand ... why aren’t the default settings of an account more secure and private?

They are (for the most relevant definition of your question).

Specifically a Facebook app you choose to install can no longer see any of your friends information. That was done in 2014 before any of this happened, more details and timeline here: https://www.facebook.com/boz/posts/10104702799873151