I'm not a blade expert. However, I think you have to consider other factors as well.
You cannot generalize and say whether ATS-34 is a bad steel. It depends on the manufacturer and how they utilize ATS-34
You have to consider:
1. The tempering process. The more a steel is tempered, the more rigid it becomes. However, there comes a point where it may border on being brittle. That would go for any steel, not just ATS-34
2. Blade design: thickness, structural integrity, etc. I would expect the thinner ATS-34 blade on my Gerber Covert to give out before the blade on my BM-710 Axis. And I dare any staple to come up against the thick "commando"-style blade on my SOG Magnadot (actually that's 440A, but you get the picture).
3. Knife use. A knife is for cutting. It's not a prybar, a staple remover, a chisel, or the substitute slotted screwdriver. Of course it will malfunction if it's used in a way that it's not meant for. REMEMBER: If God had meant the knife to be used as a chisel, he wouldn't have invented the multi-plier!