For me, high cadence works on some stretches, whereas a higher gear/low cadence works on others. Certainly, I prefer spinning when climbing, but there are some uphill stretches of road where I find a high cadence just doesn’t work.
I don’t think the high cadence thing has been debunked at all, but it’s not a universal technique and therefore needs to be used appropriately, based on the physiology of the rider and the terrain.