I don't know. My powerlifting experience is really colored by frequent injuries (not usually lifting related) that forced me to take breaks, so I never got super strong. Maybe if I'd been able to lift consistently for years I'd place more value on it.
In general though I think you may have a point, powerlifting is great for establishing a base of strength but the benefit of higher maximal strength tapers quickly relative to power endurance for grappling. Now clearly a stronger man can lift a lighter weight more easily and frequently than a weaker man, but that strength usually comes with mass increases that somewhat hamper the utility of the strength.
Let's take the case of lifting a person of your size for a throw. If you weigh 180 and can squat 180 15 times, and you lift your way to being able to squat 180 30 times but now you weigh 220, the utility of that additional strength is minimal since now your sport requires you to squat 220 as many times as possible because now you're picking up dudes your own (larger) size. I feel like kettlebells give you the best ratio of power to endurance you're likely to find, plus I've found they help my joints and general recovery whereas powerlifting was always a huge energy sap.