My system (MBP, 4 GB of RAM) works beautifully most of the time, but I noticed that sometimes when I went to a new tab in Chrome, there was a multi-second delay. I opened up Activity Monitor, went to a new tab, and noticed that my disk activity had spiked. I figured that the memory system was swapping in/out a lot of pages, so I looked at rough memory usage, and saw that the Shockwave Flash plugin had close to 1 GB in RSS. I then realized that using YouTube as a music player is probably not a good idea - Flash was designed to run as the main thing you're doing, not in the background while you're doing other things. I killed the tab, and I had no more problems.
Blunt tools can still be useful. The problem isn't the tool, it's the knowledge that people have when they use it. For example, I know that RSS overcounts, but I also suspect that the Flash plugin isn't sharing enough to make a big dent in 1 GB. And, it turns out I was right.
You wrote an excellent explanation above about modern memory systems, I find it strange that you're harping on this particular point so much.