Not necessarily. I would amend that statement to include two active, caring and involved parents in the home.
I think that two-parent households are certainly more stable than others - I grew up in that kind of household, as did my wife. We have seen, however, many households where one or both parents are not active in the development of the children; they just plain don't care.
Those are the parents who do not get involved in their children's education; they just let the children run wild. And when they do get involved in schooling, it's to complain about their children not being able to wear their $75 pants that fasten about the crotch as opposed to the waist; or to complain that a vocabulary word is offensive. There may be two parents in that household, but the household is not a constructive one.