For some reason the myth that in the old days of the internet people used "handles" or nicknames and not real identities crops up here all the time. I can only assume people making the claim weren't on the internet in the 20th century and/or were on AOL.
On the Facebook of the 1990s, Usenet, people routinely posted with their real name/identity and real email address, and message headers showed each server the post passed through from its origin, the IP address of the poster (which could and did result in doxxing) and often an "abuse@ISP" email address to complain about the post/poster.
On the Facebook of the 1990s, Usenet, people routinely posted with their real name/identity and real email address, and message headers showed each server the post passed through from its origin, the IP address of the poster (which could and did result in doxxing) and often an "abuse@ISP" email address to complain about the post/poster.