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