There exists a mod called ClassicCritAdd, made by NetherCrowCSOLYOO, which allows Predatory Instincts, Harvester's Scythe, and Shatterspleen to grant their 5% Critical Strike Chance for every stack instead of only the first. It would be very handy if there was a config option for Ceremony of Perdition and Devil's Cry that did this same thing, to keep things continuous for users of both mods like myself.

Done! Starting from 2.1.7, you can go into the Gameplay config and set "Initial Crit Stacking" to True to do this