Millions of Jews followed Moses into the Sinai desert to build an intentional community over 3,000 year ago and the project is still going today. Even more remarkably, this community grew out of a single family. Most of the intentional community projects of the 19th Century are explicitly modeled on this.
I'm guessing this was an intentional omission.
That absolutely did not happen. If anything like the Exodus as written happened -- and there are plenty of reasons to doubt that it did -- it didn't involve millions of people, a number which the Bible doesn't even claim and which would be implausible for the Hebrew population in Egypt at the time.
And lots of people contend the number is not meant to be interpreted literally: http://www.aish.com/atr/Number_of_Jews_at_Exodus.html
Your source does not, in fact, contend that, it takes the number of adult males literally, reports the larger figures as extrapolations of the total population from it, including a specific figure of around 3 million in the Exodus out of 15 million Jews (about twice the population of modern Israel) that were in Egypt at the time of the Exodus.
There being 3 million Jews in Egypt at any time that would fit the Exodus is fairly implausible; 15 million well exceeds all estimates I've seen of the plausible total population of Egypt at any such time.
Now, certainly, that number shouldn't be taken literally, and there's good reason to doubt whether the outline of the story beyond the number should be, either, which is why it makes not to cite it as a historical example of, well, anything other than a religious myth.
Most secular academics do see the Exodus as legendary, but not mythical. You've heard of the Hyksos: https://en.wikipedia.org/wiki/Hyksos Striking parralells . . .
Please don't assume bad intentions
A century of research by archaeologists and Egyptologists has found no evidence which can be directly related to the Exodus captivity and the escape and travels through the wilderness
Which dismisses a "century of research" based on a single little citation:
Meyers 2005, p. 5.
Which upon visiting the book, provides the same blanket statement at the bottom of the page, and is itself a citation to yet another external resource.
Did you even bother to investigate the "lack of evidence" claims yourself, or did you just assume the entire black hole of citations was correct?
And as a religion, lasting 3000 years isn't that unique. Christianity and buddhism are very old too.
Mormons are one such community.