I'm half-joking, because complaints about "seed oil" tend to degrade to "any plant derived oil other than olive oil", and a lot of people lump in non-seed-based oils like soy, peanut, and avocado. The most common complaints I see are either about plant based oil production processes being unnatural or including harmful additives (often by people who unfairly compare traditional small scale butter and animal oil production to modern industrial grade oil production, rather than more accurately comparing modern animal oil production to modern plant oil production or traditional animal oil production to traditional plant oil production) or about different ratios of various types of fats and acids among seed oils vs animal oils (claiming that seed oils are higher in alleged "bad fats" and animal oils are higher in alleged "good fats"). Personally, I think that most of the argument comes down to kneejerk reactions to veganism and vegetarianism, since the people who push against seed oils tend to be involved with conspiracy theories about the government trying to force everyone to become vegan, and often view animal fats as good just because it pisses vegans off. Whatever valid arguments people have against particular types of oils get drowned out by these stupid culture war arguments 99% of the time, and those arguments against specific types of oils get stretched to include literally any plant derived oil (other than olive oil) regardless of whether or not it's actually applicable. I think that olive oil wouldn't get universally singled out as the only acceptable plant based oil if it wasn't just a stupid culture war thing.