Watch from 4.15 onwards. Dante spontaniously shifts between Limbo and Reality with time dilating back and forth throughout the scene. He doesn't engage Devil Trigger, and it's not a Nephilim power because Vergil is locked into Reality as it happens.
You can't just call a case of characters getting abilities for no reason a "specific scene mechanic". It's traditionally referred to as Awful Writing.
Sometimes they did interesting things with that to diversify the gameplay in classic DMC. Remember when you got the imperfect power core in 3, and it drained your health constantly but gave you constant Devil Trigger as a pay off? It took existing mechanics and an environment you had already explored and put a new twist on it to keep things interesting.
Fetch quests can be frustrating, but like escort missions and QTE, it's a question of how the game designer approaches and employs the concept in order to enrich the gameplay experience and even deliver something new occasionally. Just look at RE4.
Dude, did you play Soul Reaver? Crystal Dynamics was pulling this mechanic off fourteen years ago on the PS1. Tech is no excuse whatsoever, and if you think reality-shifting would inhibit "hack'n'slash" gameplay:
Defiance is basically a DMC game with
actual Shakespearean acting. You should play all of Legacy of Kain, it's really good stuff. Except Blood Omen 2, that was kind of mediocre.