Majority incel theory posits that most people, or at least most men, who describe themselves as love-shy are in fact involuntarily celibate (incel). This school of thought has two main factions of theorists: The looksist faction and the love-shy faction.
The two theories
The looksist faction believes that most love-shys are in fact incels who refuse to admit that their physical appearance is what inhibits them, and not their love-shy personality. Alternately, they argue that love-shys have only developed a love-shy personality due to being rejected for their physical appearance. The reasons given by the looksists vary. Most looksists claim that love-shys do not want to admit that their D/S/R fate is held captive to something so ironclad and difficult to change, and would rather believe that it is due to something theoretically more malleable, like personality. Many love-shys dispute both the objective evidence of this claim and the notion that they are taking unwarranted refuge to a more malleable idea, believing it to be an insult.
There is some evidence that physical attractiveness helps with social networks and the D/S/R realm, and Brian Gilmartin has stated in Shyness and Love that love-shys tend to be physically unattractive, so the theory that physical attributes play a part does have some merit. However, looksists believe that looks are almost entirely to blame, and tend to dismiss notions of personality, in conflict with Gilmartin and others.
Not all looksists adhere to the majority incel theory. Some are adherents to continuum theory, while still maintaining that physical appearance is the major problem.
Some love-shys believe that love-shyness by default should be categorized as part of involuntary celibacy, since most love-shys are by definition involuntarily celibate. Many mainline Gilmartian love-shys disagree, as they believe the primary problem of love-shys is a lack of companionship, and not the lack of sexual activity. Asexual love-shys also disagree with this categorization due to their having no desire for sex itself, but still desiring affection and companionship.