Currently I have plans to give organizers tools to track no-shows, as well as the ability to "check in" people.
Do you have specific ideas about what would have been most helpful to you as an organizer?
You don't need to make the points visible to the attendees, just to the organizer or maybe make that an option. Since this involves people actually showing up, it's less likely anyone will try to game the points system like on Reddit. You might want to do meta points too so a user who is a chronic problem in various groups is shown as unreliable to organizers in new groups they join. That also goes the other way, making users who are good attendees in their groups look good starting off in any new groups they join. You'll need to experiment with the points for a while to get it right but I think this type of feedback is essential for both the organizers and attendees to weed out undesirable behaviors.
That said, a deposit would probably work even better. E.g. you put up something like a $10 deposit to RSVP, and are charged the full amount if you no-show, but only a nominal fee if you show up.
Similar to late pickup fees at daycares that sometimes increasing the amount of late pickups, as rich(er) parents view that monetary penalty as a price worth paying to avoid moral blame.
I think a community-wide karma/reputation system would be more powerful as suggested by someone in the comments here.
1. Source: I'm that type of person :-P