MMF or MFM just seems to work out better. FMF is really fun, but it's difficult to keep all 3 people involved. For a man trying to satisfy 2 women, he may need a day of rest afterward.
This board has a lot of MFM threads because that seems to be the direction that a lot of couples migrate toward. It's easier to find a single man than a couple or single woman. Much easier. Since to pool is so deep, there are a lot of gems. Just have to know how to mine.