This is baffling to me. Most of the parties I went to in high school, college, and my 20s were in people's tiny apartments, small rented houses, and small yards.
Maybe expectations changed? Now it seems more like people feel the need to get ready before going out, to bring something, to pre-coordinate to arrive with a group of friends, to have a lot of space, to have everything pre-cleaned and ready to be the background in photos, and maybe even to have a meat and cheese platter that gets posted to social media. It seems there's much less willingness to just go places, be cramped, and just hang out.