Actually it can. My older Springfield had no hammer safety and to my knowledge only very early 1911s have this safety and series 70 and 80 and beyond in colt have one.
Not sure what you mean by "hammer safety". Do you mean a firing pin lock?
So yes if the spring holding the firing pin back is weak it can cause a light primer strike making it fire which is a very bad idea.
If the spring were light enough to allow the pin to indent the primer if dropped with hammer down it would be even more likely to indent the primer if carried cocked and locked.
With hammer down the spring would be in preload condition.
With hammer back and no preload on the spring the pin would accumulate inertia in its travel.
In either case if a spring were so weak as to allow the pin to indent a primer if dropped then it would do the same when the slide was released when loading a round, or cause doubling or full auto bursts.
Ammunition intended for autoloading weapons are supposed to have stout primer cups. If a primer is ignited by a very light ding or vibration then its a defective primer, and it would have fired whether hammer was down or back and locked.
Defective primers of that sort have caused rounds to go off in the cylinder of a revolver when recoil of a round fired bounced the unfired cases against a recoil shield that had dings and tool marks.
After all the recalls of Federal ammunition I no longer trust their centerfire ammunition of any caliber, and certainly not for an autoloader.
You occasionally hear of slamfires of SKS rifles that aren't fitted with a firing pin return spring.
I nearly had one myself.
Luckily the ammo I was using was Russian milspec ammo with stout primer cup and it was relatively insensitive.
When I single loaded a round with muzzle down then ejected the round unfired, I found the primer deeply indented. Had this been a commercial sporting rifle primer it would have almost certainly gone off.
Theres no scenario I can imagine where dropping an SKS (short of it falling from the roof of a three story building) could generate the velocity of the firing pin capable of denting any non defective primer that deeply.
The speed of the bolt slamming forwards on the other hand is much greater than speed of the rifle in any sort of foreseeable drop of a rifle.
The resistence of stripping a round from the magazine slows the bolt enough that such indentations are less likely, but slamfires have happened regardless.