No, they’re not.
Small, lightweight throwing knives are likely to bounce back at you on bad throws against wood targets. My son actually had one of those cheap 5 1/2″ Ridge Runner knives bounce back from a half spin throw and stab him in the cheek. His 6″ Perfect Point knives also bounce hard.
But when we throw my big Cold Steel throwers — all of which are 12″ or longer and are pretty heavy — they don’t really bounce at all.
So yeah, it seems counter-intuitive, but large throwing knives are actually much safer than small throwing knives.
Hint: To minimize bounce, always throw small knives (8″ and under) at cardboard targets or cardboard sheets laid over your wood targets.