I guess I had it wrong about the table insert being part of the problem. I just realized that my Delta Uniguard Blade Guard actually delivers an intermediate option for the problem under discussion. My blade guard affords the ability to use just one side of the blade guard since the two sides of the guard are hinged independently and can be adjusted laterally. In the situation where the right side of blade guard would otherwise contact the fence or interfere with the cutoff, it can be adjusted to be farther away or swung completely out of the way. Swinging it out of the way would diminish the protection from that side, but it's such an unusual circumstance to position it out of the way, the operator would be alert to the missing half of the blade guard.
Just some input on the human vs. device discussion. I design medical devices for a living, and part of my job involves human factors, or taking into account the physical and cognitive abilities and limitations of users. Yes, it is the responsibility of the user to perform tasks in a safe manner. But the reality is that humans are not perfect. They get distracted, tired, lose focus during repetitive tasks, etc. The user and the device are a system, both should contribute to the safe execution of a given task. To polarize that it is all one or the other misses the complexity of the situation.
Devices and tools should be designed so they mitigate where they can against dangerous situations and draw attention to hazards that cannot be mitigated. It should be done in a manner that doesn't lull someone into a false sense of security but allows them to concentrate on the task at hand. This isn't easy in all cases but it would be the goal.
Those are my thoughts. I just lurk here trying to because I am a novice woodworker but do have some knowledge in this realm.
I took my blade guard off the first time I setup my cross-cut sled and haven't looked back. I'm not saying this is the correct answer of course, just that I felt the guard was a pain to install and adjust and didn't do much more than get in the way. I think that is to be expected because the complexity of a real good guard would be very high and very costly, so the manufacturers slap on something that is more of an afterthought than anything else and they are protected from lawsuits. The world needs a better guard system for a table saw. Something more adaptable to all the myriad of cutting situations including the use of cross-cut and miter sleds to ripping and dado blades, blah blah blah. I don't have a riving knife either - maybe I should have?? I'm not even sure where to find out if I can get one for my Rigid table saw.