I would probably add entries for things relevant to MusicBrainz. A lot of (esp. stand-up) comedians have released CDs, "audio books", or have releases on Spotify/iTunes/etc., so I would say that these comedians are "MusicBrainz relevant". If they performed at some festival, I'd say it's then also relevant to MB to record this. "Non-MusicBrainz relevant" comedians performing at the same stage I wouldn't create as MB artists just for the sake of the Event, but they can still be noted in annotation or (unlinked) in the set list.
Re: b-boying and hip hop events, I actually have added one of these:
For this, I only added the DJs playing though. I would also add DJs for other b-boying, writing, or similar hip hop events that do not per se feature the musical performance as the main act, but still has one.