It’s very common in Powerlifting programs to utilize movements outside of the competition lifts for hypertrophy purposes. The trend lately is to utilize the competition movements and their close variants for strength and movements that are less specific exclusively for hypertrophy. Some examples of hypertrophic exclusive movements would be front squats, rows, Close Grip Bench Press, etc. While it makes a lot of sense to use these movements for building muscle I think it also makes a lot of sense to use these for building strength as well.
Strength is specific to the joint-angle it’s developed in. That’s why doing quarter squats will not greatly increase your full squat. By quarter squatting you’re leaving out a large set of joint angles that come into play during a full squat. When we perform accessory exercises we’re moving our muscles through joint angles similar to but different than our competition movements. By training accessory movements for strength we can ensure that we’re strong in these alternative joint angles. This has the affect of making our strength more resilient; if we stray from good movement patterns we’re still strong enough to finish the lift. This also has the effect of increasing our base strength in the accessory movements allowing us to ultimately perform more volume over time.