Modern anchors and carabiners are designed to take the load on its spine, which maximizes their strength. However, that's not always what happens nor are the ideal conditions of the lab are what climbing equipment is usually exposed to. Carabiners and cold shunts can take 25-30kN where a 200lb climber exerts less than 1kN force statically. The issue is not with holding weight, but taking on dynamic forces in the event of a fall, so much so that ropes have to be retired after roughly dozen UIAA factor-2 falls[1] because they lose their dynamic properties.
I don't think making grooved anchors and cold shunts makes that much sense because in the event of a fall, the rope or carabiner supporting you to that shunt is absolutely not guaranteed to stay in place. I can say I've taken a few 20ft whippers that knocked the protection around.
I think what's much more important is climbers' lucidity on the rock and following established procedures. Whether a piece of protection can support the weight of a large truck or a large truck and some tires is less important than whether a climber followed all the proper procedures to minimize their risk exposure.
Failed equipment accounts for a negligible percentage of all climbing accidents.
This is extremely important to note. I would absolutely not buy a notched carabiner any time soon, and as far as I am aware, nobody makes them for climbing purposes.
However, as a counterpoint, it's rare that people take big dynamic falls on rappel anchors, as you don't usually climb above them nor have the kind of slack when finished with a climb that would cause this. Even so - I still prefer the idea of a simple, crazy strong, anchor.
I don't think making grooved anchors and cold shunts makes that much sense because in the event of a fall, the rope or carabiner supporting you to that shunt is absolutely not guaranteed to stay in place. I can say I've taken a few 20ft whippers that knocked the protection around.
I think what's much more important is climbers' lucidity on the rock and following established procedures. Whether a piece of protection can support the weight of a large truck or a large truck and some tires is less important than whether a climber followed all the proper procedures to minimize their risk exposure.
Failed equipment accounts for a negligible percentage of all climbing accidents.
[1] http://www.theuiaa.org/