Mm yes, reddit started with out with tens of thousands of users over night.
I think the situation here on lemmy is pretty comparable to early reddit. People forget it started out as mostly a nerdy programmer centric site as well, and then grew from there. It's a bit jarring to see people here insisting on artificially creating communities and pushing/guiliting people into posting more just to bring the numbers up. "the narwhal bacon's at midnight" (although it was always cringe) started because reddit was a niche site less known than 4chan to begin with, so it was just a nonsensical dog whistle.
Do I miss the focused subreddits around specific topics? Sure, but I also think they will come naturally with time if lemmy survives just as they did with reddit. And the whole reason we're here today to begin with is because of an unsatiable hunger for growth.
You will still have private/public sections, interfaces (unless you class them as inheritance), classes and instances, the SOLID principles, composition over inheritance. OOP is a lot more than just large family trees of inheritance, a way of thinking that's been moved away from for a long time.