I think the problem stems from the inconsistency of service, so while nominal 100Mbps should be adequate for common use, there are times when that service as delivered drops to much lower levels. Buffering, pixelation, stalled performance are all symptoms. SO, to avoid the dips in service, we up the ante. If dips at 100Mbps drop to 10Mbps, perhaps dips in gigabit service drop to 100Mbps. So we buy “up” to avoid the lows.