"The hand being part of the locking" idea doesn't make sense to me. You can't predict how you'll be holding a tool for a variety of tasks...
And
NOW something has just hit me... Once I was on a
very faraway trip on my bike (as in, a 400 miles bus ride kind of far), and the bike's chain jumped its gear, and somehow wedged itself viciously between the frame and some other part. It was wedged-in incredibly tight, from a full power pedal stroke, and NO amount of effort would make it seem like it would even consider moving... No tool was adequate because of the narrow space the chain was wedged in.
And
then I though of something and pulled out my Cold Steel Pro Lite, opened it, and wacked the spine on the chain, spinning the thing by the tip of the handle and hitting with its prominent humped spine on the chain as hard as I could... Finally, after several dozen wacks, the chain came loose...
If I had not freed the chain, the wheels of the bike could not even be turned...: This meant I could not even walk beside the bike, so I would have had to actually
carry it... This would have meant abandoning it... Not only would the trip have been ruined, but the bike would have been lost...
Aside from a recent "Survival" episode with a Randall Model 14, I now remember I considered this the most useful thing a knife had ever done for me in 30 years of carry... Given the number of online arguments I have already seen about spine wacking, I am actually bummed I did not remember this earlier... I'm fixed-blade centric these days...

(I usually treasure any event where my knives actually save the day, because they typically have decades of utter uselessness to make up for...)
I have to say when I did this, circa 2003-2005, it never even occurred to me this was damaging to the knife, or that the knife could fail... It's amazing what you can learn online...
Gaston