Ask HN: Why aren't there any Hacker News meetups in the bay area?

I know there's a reasonably regular HN Meetup group in London (the Meetup.com group has 3,400+ members), but I haven't heard of anything going on in the bay area. Is there any particular reason why that's the case? Obviously there'd be a tonne of people, so it might get a bit unwieldy, but is there any other reason no one is organizing them?