I don't think it is, actually? "Friend-slop" is a super-popular genre of video game right now (for example, indie smash-hit PEAK), typically characterised by low-friction co-op experiences with a low-fi and/or kit-bashed aesthetic
The games are the popular, but I do not think that term to describe them is that well-used nor used with that much affection :)
It’s requires a good base group of friends that you will have fun with already, and the design for the game is “slop” / cheap / lazy in that regard. But not necessarily bad.