The main reason for health benefits of fish oil, and the reason high doses are usually required to see benefit, is because fish oil counteracts the harms of seed oils.
Removing dietary seed oils would likely bring much greater benefit.
Most Americans (95%?) consume seed oils copiously, and don't even know they're doing it.
Much the same can be said about aspirin, which blocks the formation of inflammatory cytokines from arachidonic acid as its main mechanism. (Though aspirin has other mechanisms.)
Seed oil consumption leads to higher levels of AA.