That and you don’t get the P2P magic if it doesn’t marinate.
It’s like the difference between being an StarCraft player who does randoms in lobby games versus someone who plays consistently with the same group of people in rated play every day. The differences are extreme. A sense of community develops and you get to know what the strengths and weaknesses are of the people you play with.
If it’s just random players all the time none of that develops.