Back then everything was done with pseudonyms so you can just switch to a new one and ditch your old identity any time you like.
At least WRT usenet, my ISPs From: lines were in this format:
From: firstname.lastname@example.org (My Real Legal Name Goes Here)
So, no, its my real name all the time. Not so much for fidonet, etc, of course.
Just for fun I googled and the oldest usenet post I can find (which is weird, I know there's older) is me joining a flamewar in the mid 90s about what numerous Z80 active low control signals do when the CPU is reset and my insisting that having physically done this stuff 15 years previous to the flamewar that the active low control lines drift high and the people who were wrong insisting the control sigs go hi-z aka high impedance / tristate. Almost two decades later and I still don't know WTF those guys were thinking... I was there, man, they don't do that, and no amount of experience or quoting data sheets or books would convince the wrong guys. In summary, we got trolled, I guess.
The irony is there have been so many Z80 clones and Z80 derivatives and Z80 cores inside non-z80 chips like Z80 based microcontrollers and stuff, such that yes on an original date coded 1977 (or whatever) genuine Z80 from Zilog inc I was certainly correct, but there probably does exist some weird thing out there that might tristate the control signal lines while hoping the designer installed sufficient pull up resistors.