They are called potlucks or cookouts in the U.S. and they happen all the time.
In fact, they are probably a lot more common than having a huge party (so large that you have to invite people in batches of half a dozen at a time) completely planned and executed by a single person.
This article is good, don’t get me wrong, but this type of event planning is not really representative of how folk in the U.S. get together
Some summers I plan on BBQing every weekend and I throw invites out on Thursday. People typically bring something and we all have a good time.
For the parties as described in the article, I maybe go to one or two a year tops. Before I had a kid I used to host large parties like the kind described (~15 people tops though), now I just attend and contribute.
