> I (mistakenly?) think Oberon is that kind of "roots knowledge" shared between all of us, like Lisp or Forth.

Yes, I think that's a mistake. Lisp and Forth saw widespread commercial use, were hugely influential, and directly begat many other languages. While I'd expect most folks on here to be familiar with Pascal - you could say those same things about it - and maybe even know who Wirth is, Oberon basically saw no commercial use whatsoever and even in academia was basically only used at the school it came from. There's no real comparison.