Do you have sources for that? Which vegetables oils are healthy and which are unhealthy and why?
The only relevant knowledge I have is that saturated and trans fats are bad and that unsaturated are good. One source for that is for example https://www.hsph.harvard.edu/nutritionsource/what-should-you... .
If this is what you are refering to then margarine is indeed bad because it often contains high amounts of trans fat but for example coconut oil isnt good either for its high saturated fat content. Plenty of other vegetable oils should be fine judging by their fat contents rather than "really bad".