That's most of it, I guess. Intimacy is not a word that social media/internet brings to mind. If anything, I feel like people are served a false sense of importance and connectedness. The scaling is an illusion. No one cares if you leave the internet.
The principle issue is he presumes that intimacy, what he calls "density", scales independently of "size". And he presumes it early, and he presumes it often. A better way to look at it - the model that every single bit of sociology supports - is that the larger your network, the more dilute it is. If "Social scaling = (size)x(density)" then size and density are inversely proportional which holds "social scaling" to be a constant. Which, again, holds true for any anthropological study you care to run. Dunbar's Number will not be cheated. So. Hold "social scaling" to be constant, as all empirical evidence to date has demonstrated. Rao's assertion that GenX is somehow double the boomers and Millennials are somehow double GenX, what he's actually asserting is that the "density" of social connection for GenX is half that of boomers, while GenZ has only the most filimentous, tenuous connection to their peers. I don't think that's accurate. I don't think you can say someone is double someone else based on metrics you just pulled out of your ass. But presume that all the different methods and avenues to communication that we deal with these days require connection to more people - it would therefore make every connection more tenuous. If I am required in my day-to-day life to interact with 500 people, but my buddy John is required to interact with five, it's likely that John has a higher "density" of connection to the five people in his circle than I have with my five hundred. Humans are a fundamentally limited resource.