Nono, a liner-lock is perfectly capable of being built with sufficient detent, I'm pointing out that the strength of that detent relies greatly on the size/shape of the ball: deeper fit with steep slope = harder to dislodge, even with weak spring tension, because the blade tang is pushing up that slope to move the ball out of the way. If the ball is too small, the detent is weak unless the spring-pressure is VERY strong (i.e. very diffcult to actually open the blade for use) and even then it is a very short travel-distance for detent to be overcome and all that spring-tension is for naught.
For axis, cbbl, back-lock, even button-lock (though again spring-force is sideways rather than directly applied), the spring is usually holding a much larger object directly in the path of the tang's motion. Even with a much lighter, weaker spring, the sloped-tang must proceed with consistent force against the spring-powered object for a longer time before breaking free of the spring's influence, unless the user applies force against the spring and flips the blade out.
Since it doesn't take much time/distance of force application to overcome a liner/frame-lock's detent, the spring must be that much stronger to prevent accidental opening... and it commonly is not. Even a single omega-spring is sufficient to keep the lock-bar forward on an axis-lock - not much strength at all - and it reduces the likelihood of accidental opening because applied force must continue until the tang achieves a neutral position against the lock-bars spring-pressure trying to close the blade.
Not arguing for the sake of arguing, just talking physics and lock designs.
