I think FB groups at the very least are taking over and maybe smaller individual type groups are you say. I wouldn't agree that there is a high ratio of narrow minded people on those particular sites I mentioned anyway, there is always a couple of trouble makers but you can spot them pretty quickly and just avoid.
Regarding moderation there is very little on rollercoaster or heymammy, the very odd time a mod has to step in about anything. I have to say I joined those sites in the cooking section for various reasons back when but stayed for the general discussion which can be very interesting and enlightening on subjects I would not have been that familiar with. A great place too to ask advice on a product/service etc.
In general they are more information sites than discussions, usually most helpful with all sorts of queries, yes there is the occasional cranky topic and in fact the only thread I can recall being deleted by mods in recent years was one about a certain high profile couple and their arrears. Unfortunately it deteriorated so far it had to be removed, quite a lot of people on those sites have had their own money troubles through the recession as in general I do think the average family income on them would be middle of the road with a lot of stay at home mothers (and it is mainly women on those sites obviously) and part time workers so it hit a chord that someone could live rent and mortgage free for many years.