If there was a Reddit/Lemmy style website (where people create communities for various subjects but it’s all available from the same website using the same credentials) with forum style discussions

Isn’t this just Discourse?

Well there is a phenomenon where your brain will make sound and sight “match up” even when it shouldn’t. Like if you hear and see a basketball bouncing 75 meters away, the sound should have about a 0.25 second delay. But your brain will make you perceive the sound as happening simultaneously with the ball hitting the ground, despite the fact that you could not perceive the visual and auditory sensations simultaneously. If you go further away with the ball, eventually there is a threshold where your start perceiving the delay. The auditory and visual sense would need to be somehow linked for this phenomenon to happen I’d say.

I guess it’s the brains way of matching visual and auditory cues to try to make a better picture of the world. The brain is basically saying “that sound came from the ball” and you don’t even need to think consciously to know that.

Can they actually explode?

True is some of this, I’ve been cast iron my whole life.

I’ve seen some mods power tripping just like good old Reddit.

The difference is that when that happens on Reddit, you can’t go anywhere else. On Lemmy, you can go to any other instance and do it better if you feel the mods elsewhere are bad.

I need to perform a magic trick to make my feed “better”. At least it’s not that addicting

Lemmy’s feed is intentionally (or I think it is intentional at least) worse in this aspect than Reddit’s feed, in order to not be as addictive. Take that how you will.

Maybe what I see as red is actually what I see as blue to someone else.

This is a very common interesting thought, but what I’ve started thinking is even more interesting is this related thought:

Why does red look like it does, to you? I’m not concerned with how other people see red here, I’m just thinking about a single person (me or yourself, for instance). Why does red look like that? Why not differently? Something inside your eyes or your brain must be deciding that.

You could say “oh it’s because red is this and that wavelength” but what decides that exactly that wavelength looks like that (red)? There must be some physical process that at some point makes the qualia that is red - but how does it do that? The qualia that is red seems to be entirely arbitrary and decidedly not a physical thing. It is just a sensation, an experience, a qualia. But your eyes/brain somehow decides that ~650 nm wavelength translates to exactly that qualia. What decides that and how?

So what you meant to say is that you don’t see a difference above 60 Hz. But other people definitely can tell the difference. Don’t generalize on everyone based on your own experiences.

Do you think that the conversation around, e.g, python programming or wood turning techniques will vary so much that it warrants many specific flavors?

I don’t see why not. Human culture is like a fractal after all :P. At least I don’t think we should discourage creating different places for the same topics, because different approaches is part of decentralization.

for the cases where the culture is more-or-less universal

When is this ever true? The idea of a “universal culture” is exactly what I mean with this encouraging centralization. Even a specific community (subreddit) on a centralized service like Reddit will have a specific culture that is not in line with any “universal culture” (it’s likely to be skewed towards whatever culture exists in western english-speaking countries, just to mention an example).