sites like meetup.com or reddit can be great for that sort of thing
The problem with all these sites for using them to meet people imo is that they're too open. If you spent the time to get to know everyone you want to meet it would probably be fine but at that point you'd have spent hours upon hours forming virtual friendship, which to me defeats the purpose of casual meetups.
I'd love a site that lets you set strict and sophisticated filters. Maybe with the option to quiz users and sort out those who can't give interesting answers to certain questions. Not sure why no one's attempted to make that yet, the obvious advantage of the digital world is that we can go through large numbers of individuals, filter the noise and match exactly the ones that are suitable for each other based on shared interests. Yet the best we got is swiping left or right based on someone's photoshopped profile picture?
> Being able to prescreen is less friction than spending time meeting uninteresting people.
This is probably true for some individuals (e.g. those with social anxiety, or those who work 16 hours a day or something), but certainly not all. Even uninteresting people are often moderately entertaining for a short while, which is much more than I can say for taking an online quiz.
Additionally, there's a bit of a chicken-and-egg problem regarding the reputation of the group itself. If I can be pretty sure ahead of time that being admitted to the group will be worth it, then I will probably suck it up and take the quiz. This pretty much requires someone who is already a member convincing me. Otherwise it might well turn out to be a ghost town, or full of holier-than-thou nerds, or just not a fit for whatever other reason. I wouldn't want to go through a prescreening process just to find that out -- easier and more fun to just stick with meeting randos.