The consequences of crevice corrosion are generally more severe than those of pitting. A crevice tends to be relatively deep and narrow, whereas a pit tends to be shallower or wider.
That geometry means the reduction in a part's effective thickness can be significant, cutting its ability to carry the load or meet the pressure rating it was designed for. Depending on the depth, shape and location of the crevice, it can also act as a stress concentrator, greatly increasing the likelihood of it behaving as a crack, propagating, and causing catastrophic failure.