Yes and no, I think. Physical space has some constraints that counter this in a way online spaces don't. Take a place like NYC, for instance, where there are so many people, from so many parts of the world, that it arguably begins to "approximate human culture and interaction as a whole." What you see here is that people start to subdivide the space and agree on expected behavior -- in public spaces, like the subway, people by and large try to reduce interactions. Then there are public spaces that are pseudo-private, like bars or cafes or restaurants, but each have their own understood rules -- at a bar you can start to talk up a stranger, at a restaurant you don't just walk to a random table and join in a conversation. There are also many private spaces -- apartments, or your own room in an apartment shared with roommates.
Contrast that with the typical online space, where it's not just that there are lots of people, but also no constraints. It's the equivalent of going on to a subway and yelling at someone about politics...
I don't think the problem with the modern internet is scale so much as a failure to build some constraints into its design. Everything is public at a very loud volume.