Most seed oils in the Western diet come from fast food and the fryer which increases the chance of lipid oxidation.
We need both omega 3 and omega 6 but the Western diet is so heavily skewed towards omega 6 that it's killing us.
https://chriskresser.com/an-update-on-omega-6-pufas/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4808858/