There are an incredible number of people out there using "email@example.com" as a bogus email address
whenever some lame web site
requires an email address before it will let you see its lameness.
I can only presume the original holder of the "firstname.lastname@example.org" account has been forced to abandon it after being buried in an avalanche of spam. (I always imagine "Larry" as the Larry from "Three's Company" for some reason.)
However, lame websites continue to accept "email@example.com" as if it were a real address.
Long live firstname.lastname@example.org!