Today is the 12021th of September 1993.
Another way of thinking about it: Suppose the exact same userbase had joined Usenet, but they trickled in gradually instead of flooding in all at once. How much would that have changed the outcome?
FWIW I used to think it was human capital, but have updated more towards cultural explanations. For example, it seems fairly common for academics to make fools of themselves online nowadays.