The truth is, for the 98% of what we use a knife for most, a lock is not needed. If you know what your doing with the knife, a back spring is not even needed. For the past year, I've been using a knife that a fellow forum ember in Sardinia gifted me. It's a Sardinian friction folder called a resolza, a style of knife popular on the island for a few centuries. It has no springs, no locks, and it cuts great. The very forces at play when using the knife keep it open. Sardinian shepherds and farmers use this knife, which is very similar to other European f riction folders. Growing up suing typical American style slip joints like scout knives and stockmen, it was a little unnerving at first, but once uyou get used to it and see how it works, it actually feels better than a slip joint.
I've been using pocketknives for about 60 years now, and I've never chad a locking blade knife. I cut myself once on the old scout knife my dad gave me when I was 12, but since I learned that lesson, it never happened again. In my life I've carried and used a knife here at home, North Africa, Europe, and Southeast Asia. I've never found the lack of a locking blade to be a handicap, but many times I appreciated having a couple of blades on hand in one package.
Each to their own, buy unless you're stabbing into something, a lock on the blade is not really needed.
When I was in the service, I saw all kinds of workers from the local populace using non locking folders for heavy work. I was in the engineers, and we did construction work all over. Germany, where I saw local workmen using the old Herders sodbusters made there in Germany. In Libya, at the old Wheelus Air force base, local arab workers used the Douk-Dou for everything on the construction site. No locks, and no severed fingers. But modern society has become safety gadget conscious, and that supersedes intelligent thought in action. Folding knives go back to Roman times, and yet locks were not common until Buck came out with the 110 in 1963. People just gave a thought to what they were doing. All the millions of Opinels made since 1890, and the loving ring was not added until 1955. Yet somehow generations of people using this knife kept all their fingers.