First off, I don't believe anyone is of the opinion that mistake(s) were not made in this incident. If you were to look at every Avy fatality, I'm sure every one, had some form of mistake leading up to it. What myself, and many of the others took issue with in the other thread, was the crassness and lack of respect in which the accusation, and assumption of those perceived mistakes were, by one who had nothing more than pictures to go off of. But enough about that thread.
As has been said already, education and proper judgement are the two best weapons in avoiding being caught in an avalanche. Avy bags, beacons, RFID embedded gear, etc. are all great items. However, while they MIGHT save your life, after an avalanche, they are not going to prevent you from being in one. Knowing your terrain, proper group riding techniques, snowpack, and utilizing avalanche forecasting resources, COULD. Ultimately, it is up to the rider(s) to make smart choices in where, when, and what they ride, to mitigate the chance of being caught in a slide. One of the best things I have ever done to help my riding, was taking Mike Duffy's course in Silverton. I had taken Avy classes previous, but they were never in active avalanche terrain, and were always directed at skiing. This is something I would highly recommend to everyone that can (not necessarily in Silverton, but one in the mtns focused towards snowmobilers).
As was also said before, snowmobiles keep becoming more capable, riders are going higher and bigger, and everyone is trying to become the next Slednecks film start. This, like in any other sport, leads to more risk. In Motocross, it is typically broken bones. In our sport of sledding, it also includes exposure to one of natures most powerful forces. The more realization of that there is, the less tragedies we will have in the future. All that said (and I am not saying this did or did not have a role in this case), plenty of bystanders, have been caught in avalanches. Paying attention to where you stop and watch/have lunch/take picture/etc, can be just as important as where you are riding.