I agree with what you’re saying conceptually. However I don’t think stats for DTs are completely useless. Overblown? Yup. Shouldn’t be used as the sole gauge? Yup. But not completely useless. When I saw 3 tackles for Jackson, I immediately wondered “how many snaps is he seeing?” And assuming it’s a lower number, why? Is he in the second rotation?
To your premise though, if he’s a space eater taking on double teams (pause) in order to keep the LBs clean and he’s effective, stats won’t show that. Film will though.