I am guessing because fb is limited to private events generally and upcoming is still only really used by tech demographic (at least in London) and doesn't have a digg/reddit like voting structure.

I am also thinking he only did this idea to learn and test it out rather than as a serious business venture but then he should still have done a more unique concept since their are plenty out there....

Its supposed to be really fast and to the point to find events posted not by olny organizations, But events posted by individuals who are in the know....djs, bartenders, event promoters, etc... or if a you and/or a group of friends are hitting up a local bar or restaurant