An exposed hammer can usually be 'decocked' or 'uncocked' giving many (me, for instance) the feeling the gun can be rendered 'safe'. (Which is a relative term and not to be considered a final answer.) Manual safeties have this same effect, which makes the 1903 Colt seem safer and more controllable than a Glock, for instance. (This may NOT be true in all cases, but SEEMS to be so.) Hammers are so traditional and expected. I prefer handguns with hammers.
Rifles, not so much. Few bolt rifles have hammers; many have strikers, and some strikers can be lowered, example is the Springfield M1903. However, that lowering usually results in the firing pin portion resting on the primer, which is much more dangerous than an empty chamber or even a striker or hammer type gun on safety. Semiautomatic rifles (notibly the AR design and variants and copies) do not allow hammers to be lowered, requiring use of safety (which is quite positive) or empty chamber. Most shotguns of the self loading or pump configuration use a safety only blocking the trigger from being pulled, but not locking movement of the sear. Which is the basis for the old firearm command of 'never trust a safety'. Viewed in the context of the trigger block safety, there is validity in the comment. (I have two shotguns, one an 870 reserved for house defense and a SxS, used for 'Cowboy' and now limited to 'fun' and both are kept empty until need and the safety is immaterial.
