Actually they didn't. Many old timers had little contact with other shooters, and wouldn't know a good lock from a bad one. That is why the bad locks have survived. The owners just accepted a slow lock time, and misfires. They either put the gun aside after acquiring a better one- they could not sell or trade it to anyone- or they found something else to use to kill game, or domestic livestock. I still meet long time flintlock shooters who think that their guns which barely fire at all, or have a delayed fuse effect before the gun goes off is ' just the way flintlocks shoot ". They are dumbstruck when they hear and see my gun fired. They tell me they honestly have never even heard it was possible to get a flintlock to fire that fast.
So just because guns have survived through history for us to look at does not mean the folks back then knew much about them. I learned this first, BTW, in looking for a good anvil at farm auctions.Most are beat half to death, because the farmers who bought them had no training in how to use an anvil properly, and how to maintain them. I learned that from an old blacksmith I met back in 1973, and wrote my first published story about it in Muzzle Blasts. Like so many people today with no training in how tools are used, how to clean and maintain them, and how NOT to use them, farmers have been using anvils as a glorified rock, beating them with everything, heating the surface too hot so that part of the surface is annealed, chipping off edges, filing off edges, etc. The same kind of " wood butcher " work is seen with old guns all the time. That is what keeps gunsmiths in business.