Mind, I agree with you, but given the Holy Documents Handed Down By Our Lord and Savior, Paul Graham, HN... might not be the safest place to say it.
Edit: so, I'm clearly getting a lot of downs on this... maybe sarcasm in reference to PG was going a bit too far. Oh well. I'm not deleting or editing any of it, because that's sort of dishonest.
You can go to any Ruby meetup and you will see it's different than PHP meetup which both are quite different from Functional Programming meetups.
Thus I would say that it's not about the technology but about people whom you attract (i.e. culture).
I skip luck & timing, these are mostly random and one has very little power to influence them.
Finally, if you went travelling to any other country (except Austria or Switzerland maybe), the rest of the world had Facebook. So to keep in touch, you also needed Facebook, which had a better user experience. Why bother with both?
I mean, essentially all you're saying is "startup success is largely uncorrelated with the programming language used to implement those startups' products". That seems like not at all an unreasonable position.
(It's not, by the way, equivalent to the statement "choice of language doesn't matter".)