This might be true in the midwest but definitely isn't for my area, the PNW. Synthetics without a membrane will wet through, and I assure you no amount of wool

This might be true in the midwest but definitely isn't for my area, the PNW. Synthetics without a membrane will wet through, and I assure you no amount of wool sweater underneath will save you from misery when that happens (I love wool btw, literally half my wardrobe is wool sweaters). Likewise, hiking through the wet vegetation you find in many of the forests here will soak through your pants even if it's not raining. With snowboarding on Mt Hood, having a shell with a membrane is absolutely necessary on the days where it hovers between rain and snow. Probably the highest value outdoor equipment I've ever bought is a gore tex balaclava for weather like that. It's a huge difference. Some of the new soft shell materials do a lot better than synthetics + DWR, but they still fail in conditions like the above. So, similar to Chesterlon's fence, perhaps it isn't that all of us buying membrane clothing have been duped by marketing, but rather you simply don't know when it's useful.