as a friend keeps repeating
..."remember the Galloping Ghost". Replacement hardware is a lot cheaper than a critical failure.
More technically, torquing a bolt/ screw/ fastener stretches it. That's why engine bearing cap screws/ studs/ carry- throughs are replaced, for example. BUT, in most applications, you'll never see the stretch, and unless over-torqued, the tensile strength is so minimally degraded as to be a non-issue. [Once over- tightened, you have invaded the 'safety value' of both tensile and shear strength--please throw it out]
That being said, if you walk into a shop and there is not a set of bins with LOTS of new hardware -- turn around, walk away to live another day.