Lookism, otherwise known as, looksism, is a synonym of cacophobia, but without a psychiatric context. One popular forum dedicated to lookism is lookism.net. Most humans are extremely, naturally lookist.
Incels sometimes self-obsess over their appearance as dating is increasing moving online, whether via social media or online dating apps, and online men who are average or ugly get almost no luck on these sites. It is a brutal form of lookism that keeps them from getting matches.
In this increasingly dominant dating paradigm, the only way to succeed is through vanity. So you could see incels as being forced in a way to become vain to attract a partner in modern dating. The opposite of lookism is personalitism.
Looks are necessary to the formation of physical or romantic desire
Women place a minimum threshold of attractiveness on potential mates. Women also lie about the degree of importance of physical attractiveness. One could begin to bargain that while looks matter, other factors matter too. One's full attractiveness could be seen as a composite score of their attractive features. Sadly, Looks were the only factor to predict interest in speed dating. Attractiveness and masculinity also predicts a woman's chance of orgasm. Looks are highly heritable as well. There is an idea that looks only play a role in short team partnerships, while features such as personality matter more in a long-term relationships. This is not the case.