That's because half of them would replace the slide-lock scale with a regular scale, removing the lock completely. Can't do that with the liner-lock.

Personally, I couldn't stand the old slide lock. I never found it to be a reliable locking mechanism. When they came out with the linerlock models, I bought one of them and couldn't have been happier. Then when they came out with the one-handed liner-lock models, I bought a one-handed Trailmaster (now Trekker?). IMO, the best SAK they ever made (though I never really liked the serrations, so I ground them off, which also made for a much nicer point).

When they came out with that one-handed Trailmaster, I can remember thinking to myself....this should be the new Soldier's knife. Sure enough, I just bought myself a new Soldiers knife....which is just a Trailmaster with different scales and no tweezers/toothpick.