Eric, that is because on most regular PGA Tour stops, you don't have 10 of top 10 or 9 of top 10 players playing. You would be lucky to get 3 or 4. Which means if only 1 or 2 of those guys missed the cut, you would have an equivalent (For example, Wells Fargo had top 20 guys like Rory(!), Casey, Watney, Karlsson, and Dustin miss the cut line - out of 10 guys who played, ONLY 50% made the cut!!! - worse than US Open!!!).
If Congressional was playing as par 72, the score would be indistinguishable from most PGA Tour events. That pretty much survives any scrutiny, I am afraid.
Look, I have always argued that any local muni with sufficient length can host a successful Open if the greens were firm enough. Congressional greens were too soft for US Open. You can blame the weather if you wish, but I blame the people who prepared the course. The course was not suitable for a major as is.