It's more about people most people don't know who are here unless you tell them rather than you're data being secure. A different feeling then when posting with your real name and with all of you irl friends following you

[–] geissi@feddit.org 1 points 2 weeks ago

I mean using your real name does not depend on the platform you're using but more on how you're using it.
Pretty sure the majority of reddit users do not post under their real name and you could use a pseudonym on facebook if you wanted to.
Zuckerberg isn't going to check your ID when you sign up.