Here's the explanation you requested:
You typed "front rack". I assume this is a typo because our previous discussion was never about all front racks. Our previous discussion was only about the specific racks in the OP's pictures. We need to be specific because there are plenty of good front racks that do not handle poorly. It is very important that we be able to tell the difference between good front racks and bad ones (which you apparently cannot).
But anyway, to answer your question: I am physically capable of riding this type of racks, however since I have a choice in what bikes I ride, I decided to avoid bikes that handle poorly. Because I have good taste in preferring the most pleasurable cycling possible (unlike you).
Understand now?
I think your problem is you are using racks made out of a canines fecal matter instead of steel, aluminum or titanium those tend to work better as a front rack material.
My Cinelli Mash Work that I built up as the Single Speed/Fixed Gear RandoCross FunTime Machine has a Nitto cantilever mounted rack and it is fantastic but I chose a steel rack on this one. It rides just fine no issues with bag and weight and without. The Specialized Como 5.0 or other models with the Pizza Rack added rode great as well but that one is an aluminum rack not made of any sort of fecal matter.
If you have a problem with bike handling that comes with riding more and practice. I know it is working for me with mountain biking and has worked in the past with my road riding as well. When riding with a front rack it can take some getting used to so that might be a huge part of your real issue beyond the rack material. Ride more and slowly increase the weight as you start to get more comfortable.