I'll let Rick Hinderer explain it:
"The fact that the thumb stud locks up against the frame adds an incredible amount of strength to the sideways torque of the blade as the sideways stresses are being stopped by the whole handle side, thus relieving the stress that would normally be put on the pivot."
It doesnt take too much of a mechanical mind to understand this.
If you dont, grab a pen or pencil with one finger and your thumb.
Now torque, or move the pen with your other hand.
See how easy it moves, no matter how tight you grab it?
Now, hold the pen with two fingers and your thumb and repeat the test.
Make sense now?
Strider, Hinderer, and even CRK, (on the Umnumzaan), use this design.
There is a reason.
Its stronger.