It was an era of overly complex rules systems of one stripe or another. My first RPG was a MERP set my mother bought me when I was 10 or so (Middle Earth RolePlaying, which used the Rolemaster system), and it was just charts charts charts. the next was Earthdawn which my friend bought; I was maybe 13 or 14. That one made enough sense to play, and we did, and it was great.
But then I found 2e D&D, and it was so elegant and simple compared to the others it blew our minds. The Earthdawn setting was great, but the mechanics were wonky and the dice pools and steps were just clunky. D&D, with its simple "roll a d20 and add modifiers" mechanic, was astounding.
We never managed to get a sustained WoD campaign going, largely because, again, the mechanics seemed so finicky compared to the elegance of D&D. We have Castle Falkenstein a shot (based on the positive reviews it got in Dragon Magazine), we played a game called Og for a while, some of us ran Marvel Superheroes and Star Trek and even Toon, but we all came back to D&D. It was just an easier and more flexible system. Almost everybody knew how to play it, and it was simple to introduce new players who didn't.
Again, this was at a nerd farm of a high school, and we lived on campus so we saw each other all the time. But even after graduation, whose of us who went to (and ultimately dropped out of, but that's a different story) the same college kept going with it.
THAC0 was easy. The core D20 system that replaced it may have been easier, but it wasn't by too great a margin.
Interesting, thanks for elaborating!
My opinion and experience still says it's a strange standpoint although, but that1s okay, we're different!

WoD... I'd never, ever say that any iteration of WoD is harder to grasp and all-in-all more complex than any iteration of D&D. Quite the opposite, my experience says that new gamers tend to understand and learn it much faster and it's a much more flexible system, IMO. Especially with older editions, since 5e closed the gap considerably, but still.
But again, I'm not a math nerd, so our experiences are clearly differ. I'm not saying yours isn't valid, it's yours, I just say I'd never thought and don't know anybody who'd say that WoD is a more complex system than D&D 2e/3e.
Anyway, it was interesting, so thanks again!