At the top: calling out that the article says this person is a "researcher" - no, if he bought 200 Facebook accounts for $10? This person is aCRIMINALnot a researcher!
https://tech.slashdot.org/story/21/04/22/2035245/a-new-facebook-bug-exposes-millions-of-email-addresses
Article describes how in addition to last month's Facebook phone number dump of 500 million users, there's another bug which this criminal already told Facebook about, and since Facebook is fixing it "too slow" for this criminal's mind, this criminal has written a tool so others can exploit the criminal hole this criminal has found.
Just because my gate isn't securely latched, doesn't mean all my property, are belong to you.
Take off every zig.