We try to do stuff with our non-LDS neighbors, but it falls through more often than not. People have become much more private and less-prone to make new friends, it would seem. I blame the internet. We do stuff with our Mormon friends all the time, in contrast, and make new Mormon friends all the time.
MLM-type marketing used to be very common back in the 50s when everyone lived in close-knit communities. The social structure lent itself well to that type of marketing. Today, in America, that type of social structure pretty much only exists in the Mormon church and a few other communities. Hence, MLM is more common among Mormons than other groups.