I'm not entirely sure I agree.

On the one hand, I totally endorse your skepticism about claims that a particular moment in time is somehow the one nodal point that changes everything. I think you're spot on about why that myth is so appealing to people. And I also happen to believe that in any objective consideration, a whole lot more changed technosocially between, say, 1850 and 1900 than has changed since then.

Having said that, though, historically, some moments really were pivotal, at least for some domains. 1914 and 1989 come to mind. Those genuinely were civilizational inflection points - Eric Hobsbawm calls this interval "the short twentieth century." (We're still a little close to be able to tell, but I'd argue that the era that began in 1989 came screaming to a halt in September 2001.)

There's even an argument that we find ourselves in a unique moment of human history, though that one feels a little self-congratulatory to me, and even though I don't have the math to find the hole in the argument, I tend to believe it's there.

So maybe it's one out of every hundred or even thousand times that the proclaimers of a New Epoch are right. But when they are, man would I hate to have not paid attention.