Yes animal fats do go rancid. Normal people don't eat them after they go rancid because we can smell and taste the rancidity.

The oils from seeds are processed in such a way with high temperatures they become highly oxidized during the process. They are also nothing a human would choose to eat. Then they are clarified, deodorized and antioxidants added to make it look and smell like what we get at the grocery store. That is my understanding. It could be wrong. Maybe the very old style of processing that only crushed the soybeans to get the oil out would be better? Possibly. 

There are different views on the problem caused by the seed oils.

One line of thought is the above that it is mostly the oxidation end products that make it to our cell walls that are the problem and cause long term chronic inflammation.

Another popular line of thought is it is the high levels of Omega 6 in the oils. We are consuming many multiple times of Omega 6 containing fats than we would have in any human history over about 100-125 years ago. Both Omega 3 and Omega 6 are essential nutrients. We have to have them to live and we have to have them from the diet. Omega 3 tend to be more anti-inflammatory and the Omega 6 tend to be more inflammatory although both have some of both characteristics. But we need minute amounts of Omega 6 and we get buckets of them in seed oils that historically we would never have had in those amounts. Humans would have never eaten the amount of seeds to get the mega amounts we now get in the concentrated oils. That is my overall understanding which is probably not fully complete.

Some claim both are problems. Other oils can also be problematic. Even fish oil oxidizes easily and can do so sitting on the shelf. The more solid a fat is (ie not liquid) the more stable it is to oxidation. 

There are technical explanations of why the different fats get oxidized more or less easily that has to do with double bonds in the carbon chain. But I suspect you don't really care or want to know anyway. If you do care I suggest you look up professor Benjamin Bikman or doctor Paul Mason on Youtube and do a search on the subject. Both of these people are very versed in the scientific studies concerning seed oils and can give a lot better explanation about the mechanisms. Bikman does some of the studies on fat both in humans and in animals in his lab and has published a number of scientific papers on the subject. Mason was involved in a big meta analysis of published papers on the subject. They are well versed in the scientific literature on the subjects of fats in the human diet.

I don't protest anybody. It is just information a person can either choose to use or ignore for their own health benefit.