I can't argue with your points, you are probably right. What I've seen when comparing USGA and EGA systems in the past (which are somewhat similar to WHS and CONGU) is that the USGA handicap index was quicker to fall and also quicker to rise. So if your EGA has been lingering around, say, 15, then the equivalent USGA calculation would quickly go down to 12 with a couple of good rounds and just as quickly bring you back to 20. But overall and on average, the USGA handicap was always lower than the equivalent EGA handicap (putting in the same performance data).
The USGA system had that bonus for excellence, which was scrapped in the WHS, but probably over-compensated for by counting the best 8 instead of best 10 rounds. Vanity handicappers will not be affected, as they don't post any scores, once they've reached their target number.