I think the point that's trying to be made is that some people (regardless of their machines) were running the game maxed out on settings, Hi Res, sliders to the max, shadows, detailed water and terrain and so on, and were getting FPS's of 59-60 consistently. Since the lattest series of patches, those same people have had a tendency to disco more, increase in FPS drops, stutters and overall just not a lot of fun playing the game in it's current state. That's what I think has led people to comment about their leaving.
Sounds to me like they were teetering on the edge of over-taxing their hardware, and the stuff introduced with the latest patches pushed them over the edge. Now their computer can no longer keep up with all the graphics data and also keep up with the network packets, etc. Whether they tried reducing the resolution, or the graphics quality sliders, I don't know. Maybe they refuse to reduce the eye candy and are too stubborn to admit their machines can no longer handle max graphics settings.
In any case, it seems logical that it is possible for reduced frame rates due to over-taxed hardware to affect ping times across the network. But frame rates are most definitely not the same as ping rates.